Basic Java Script

AccessArrayDataWithIndexes.js

/**Access Array Data with Indexes
We can access the data inside arrays using indexes.

Array indexes are written in the same bracket notation that strings use, except that instead of specifying a character, they are specifying an entry in the array. Like strings, arrays use zero-based indexing, so the first element in an array is element 0.

Example

var array = [50,60,70];
array[0]; // equals 50
var data = array[1]; // equals 60
Note
There shouldn't be any spaces between the array name and the square brackets, like array [0]. Although JavaScript is able to process this correctly, this may confuse other programmers reading your code.


Create a variable called myData and set it to equal the first value of myArray using bracket notation. */
// Example
var ourArray = [50,60,70];
var ourData = ourArray[0]; // equals 50

// Setup
var myArray = [50,60,70];
var myData = myArray[0];
// Only change code below this line.

AccessingNestedArrays.js

/**Accessing Nested Arrays
As we have seen in earlier examples, objects can contain both nested objects and nested arrays. Similar to accessing nested objects, Array bracket notation can be chained to access nested arrays.

Here is an example of how to access a nested array:

var ourPets = [
  {
    animalType: "cat",
    names: [
      "Meowzer",
      "Fluffy",
      "Kit-Cat"
    ]
  },
  {
    animalType: "dog",
    names: [
      "Spot",
      "Bowser",
      "Frankie"
    ]
  }
];
ourPets[0].names[1]; // "Fluffy"
ourPets[1].names[0]; // "Spot"

Retrieve the second tree from the variable myPlants using object dot and array bracket notation. */
// Setup
var myPlants = [
    { 
      type: "flowers",
      list: [
        "rose",
        "tulip",
        "dandelion"
      ]
    },
    {
      type: "trees",
      list: [
        "fir",
        "pine",
        "birch"
      ]
    }  
  ];
  
  // Only change code below this line
  
  var secondTree = myPlants[1].list[1]; // Change this line

AccessingNestedObjects.js

/**Accessing Nested Objects
The sub-properties of objects can be accessed by chaining together the dot or bracket notation.

Here is a nested object:

var ourStorage = {
  "desk": {
    "drawer": "stapler"
  },
  "cabinet": {
    "top drawer": { 
      "folder1": "a file",
      "folder2": "secrets"
    },
    "bottom drawer": "soda"
  }
};
ourStorage.cabinet["top drawer"].folder2; // "secrets"
ourStorage.desk.drawer; // "stapler"

Access the myStorage object and assign the contents of the glove box property to the gloveBoxContents variable. Use bracket notation for properties with a space in their name. */
// Setup
var myStorage = {
    "car": {
      "inside": {
        "glove box": "maps",
        "passenger seat": "crumbs"
       },
      "outside": {
        "trunk": "jack"
      }
    }
  };
  
  var gloveBoxContents = myStorage.car.inside["glove box"]; // Change this line
  

AccessingObjectPropertiesWithBracketNotation.js

/**Accessing Object Properties with Bracket Notation
The second way to access the properties of an object is bracket notation ([]). If the property of the object you are trying to access has a space in its name, you will need to use bracket notation.

However, you can still use bracket notation on object properties without spaces.

Here is a sample of using bracket notation to read an object's property:

var myObj = {
  "Space Name": "Kirk",
  "More Space": "Spock",
  "NoSpace": "USS Enterprise"
};
myObj["Space Name"]; // Kirk
myObj['More Space']; // Spock
myObj["NoSpace"]; // USS Enterprise
Note that property names with spaces in them must be in quotes (single or double).


Read the values of the properties "an entree" and "the drink" of testObj using bracket notation and assign them to entreeValue and drinkValue respectively. */
// Setup
var testObj = {
    "an entree": "hamburger",
    "my side": "veggies",
    "the drink": "water"
  };
  
  // Only change code below this line
  
  var entreeValue = testObj["an entree"];   // Change this line
  var drinkValue = testObj["the drink"];    // Change this line

AccessingObjectPropertiesWithDotNotation.js

/**Accessing Object Properties with Dot Notation
There are two ways to access the properties of an object: dot notation (.) and bracket notation ([]), similar to an array.

Dot notation is what you use when you know the name of the property you're trying to access ahead of time.

Here is a sample of using dot notation (.) to read an object's property:

var myObj = {
  prop1: "val1",
  prop2: "val2"
};
var prop1val = myObj.prop1; // val1
var prop2val = myObj.prop2; // val2

Read in the property values of testObj using dot notation. Set the variable hatValue equal to the object's property hat and set the variable shirtValue equal to the object's property shirt. */
// Setup
var testObj = {
  "hat": "ballcap",
  "shirt": "jersey",
  "shoes": "cleats"
};

// Only change code below this line

var hatValue = testObj.hat;      // Change this line
var shirtValue = testObj.shirt;    // Change this line

AccessingObjectPropertiesWithVariables.js

/**Accessing Object Properties with Variables
Another use of bracket notation on objects is to access a property which is stored as the value of a variable. This can be very useful for iterating through an object's properties or when accessing a lookup table.

Here is an example of using a variable to access a property:

var dogs = {
  Fido: "Mutt", Hunter: "Doberman", Snoopie: "Beagle"
};
var myDog = "Hunter";
var myBreed = dogs[myDog];
console.log(myBreed); // "Doberman"
Another way you can use this concept is when the property's name is collected dynamically during the program execution, as follows:

var someObj = {
  propName: "John"
};
function propPrefix(str) {
  var s = "prop";
  return s + str;
}
var someProp = propPrefix("Name"); // someProp now holds the value 'propName'
console.log(someObj[someProp]); // "John"
Note that we do not use quotes around the variable name when using it to access the property because we are using the value of the variable, not the name.


Use the playerNumber variable to look up player 16 in testObj using bracket notation. Then assign that name to the player variable. */
// Setup
var testObj = {
    12: "Namath",
    16: "Montana",
    19: "Unitas"
  };
  
  // Only change code below this line;
  
  var playerNumber = 16;       // Change this Line
  var player = testObj[playerNumber];   // Change this Line

AccessMulti_DimensionalArraysWithIndexes.js

/**Access Multi-Dimensional Arrays With Indexes
One way to think of a multi-dimensional array, is as an array of arrays. When you use brackets to access your array, the first set of brackets refers to the entries in the outer-most (the first level) array, and each additional pair of brackets refers to the next level of entries inside.

Example

var arr = [
  [1,2,3],
  [4,5,6],
  [7,8,9],
  [[10,11,12], 13, 14]
];
arr[3]; // equals [[10,11,12], 13, 14]
arr[3][0]; // equals [10,11,12]
arr[3][0][1]; // equals 11
Note
There shouldn't be any spaces between the array name and the square brackets, like array [0][0] and even this array [0] [0] is not allowed. Although JavaScript is able to process this correctly, this may confuse other programmers reading your code.


Using bracket notation select an element from myArray such that myData is equal to 8 */
// Setup
var myArray = [[1,2,3], [4,5,6], [7,8,9], [[10,11,12], 13, 14]];

// Only change code below this line.
var myData = myArray[2][1];

AddingDefaultOptionInSwitchStatements.js

/**Adding a Default Option in Switch Statements
In a switch statement you may not be able to specify all possible values as case statements. Instead, you can add the default statement which will be executed if no matching case statements are found. Think of it like the final else statement in an if/else chain.

A default statement should be the last case.

switch (num) {
  case value1:
    statement1;
    break;
  case value2:
    statement2;
    break;
...
  default:
    defaultStatement;
    break;
}

Write a switch statement to set answer for the following conditions:
"a" - "apple"
"b" - "bird"
"c" - "cat"
default - "stuff" */
function switchOfStuff(val) {
    var answer = "";
    // Only change code below this line
    switch(val) {
      case "a":
      answer = "apple";
      break;
      case "b":
      answer = "bird";
      break;
      case "c":
      answer = "cat";
      break;
      default:
      answer = "stuff";
      break;
    }
    
    
    // Only change code above this line  
    return answer;  
  }
  
  // Change this value to test
  switchOfStuff(1);
  

AddNewPropertiesToAJavaScriptObject.js

/**Add New Properties to a JavaScript Object
You can add new properties to existing JavaScript objects the same way you would modify them.

Here's how we would add a "bark" property to ourDog:

ourDog.bark = "bow-wow";

or

ourDog["bark"] = "bow-wow";

Now when we evaluate ourDog.bark, we'll get his bark, "bow-wow".


Add a "bark" property to myDog and set it to a dog sound, such as "woof". You may use either dot or bracket notation. */
// Example
var ourDog = {
    "name": "Camper",
    "legs": 4,
    "tails": 1,
    "friends": ["everything!"]
  };
  
  ourDog.bark = "bow-wow";
  
  // Setup
  var myDog = {
    "name": "Happy Coder",
    "legs": 4,
    "tails": 1,
    "friends": ["freeCodeCamp Campers"]
  };
    
    myDog["bark"] = "bow-bow";
  // Only change code below this line.
  

AddTwoNumbersWithJavaScript.js

/**Add Two Numbers with JavaScript
Number is a data type in JavaScript which represents numeric data.

Now let's try to add two numbers using JavaScript.

JavaScript uses the + symbol as addition operation when placed between two numbers.

Example

myVar = 5 + 10; // assigned 15

Change the 0 so that sum will equal 20. */
var sum = 10 + 10;

AppendingVariablesToStrings.js

/**Appending Variables to Strings
Just as we can build a string over multiple lines out of string literals, we can also append variables to a string using the plus equals (+=) operator.


Set someAdjective and append it to myStr using the += operator. */
// Example
var anAdjective = "awesome!";
var ourStr = "freeCodeCamp is ";
ourStr += anAdjective;

// Only change code below this line

var someAdjective = "cool!";
var myStr = "Learning to code is ";
myStr += someAdjective;

BuildJavaScriptObjects.js

/**Build JavaScript Objects
You may have heard the term object before.

Objects are similar to arrays, except that instead of using indexes to access and modify their data, you access the data in objects through what are called properties.

Objects are useful for storing data in a structured way, and can represent real world objects, like a cat.

Here's a sample cat object:

var cat = {
  "name": "Whiskers",
  "legs": 4,
  "tails": 1,
  "enemies": ["Water", "Dogs"]
};
In this example, all the properties are stored as strings, such as - "name", "legs", and "tails". However, you can also use numbers as properties. You can even omit the quotes for single-word string properties, as follows:

var anotherObject = {
  make: "Ford",
  5: "five",
  "model": "focus"
};
However, if your object has any non-string properties, JavaScript will automatically typecast them as strings.


Make an object that represents a dog called myDog which contains the properties "name" (a string), "legs", "tails" and "friends".

You can set these object properties to whatever values you want, as long "name" is a string, "legs" and "tails" are numbers, and "friends" is an array. */
// Example
var ourDog = {
    "name": "Camper",
    "legs": 4,
    "tails": 1,
    "friends": ["everything!"]
  };
  
  // Only change code below this line.
  
  var myDog = {
    "name": "Fil",
    "legs": 4,
    "tails": 1,
    "friends": ["cats!"]
    
    
    
  };

ChangingIfElseStatements.js

/**Chaining If Else Statements
if/else statements can be chained together for complex logic. Here is pseudocode of multiple chained if / else if statements:

if (condition1) {
  statement1
} else if (condition2) {
  statement2
} else if (condition3) {
  statement3
. . .
} else {
  statementN
}

Write chained if/else if statements to fulfill the following conditions:

num < 5 - return "Tiny"
num < 10 - return "Small"
num < 15 - return "Medium"
num < 20 - return "Large"
num >= 20 - return "Huge" */
function testSize(num) {
    // Only change code below this line
    if (num < 5) {
      return "Tiny";
    } else if (num < 10) {
      return "Small";
    } else if (num < 15) {
      return "Medium";
    } else if (num < 20) {
      return "Large";
    } else {
      return "Huge";
    }
  
    
    return "Change Me";
    // Only change code above this line
  }
  
  // Change this value to test
  testSize(7);

CommentYourJavaScriptCode.js

/*Comment Your JavaScript Code
Comments are lines of code that JavaScript will intentionally ignore. Comments are a great way to leave notes to yourself and to other people who will later need to figure out what that code does.

There are two ways to write comments in JavaScript:

Using // will tell JavaScript to ignore the remainder of the text on the current line:

// This is an in-line comment.
You can make a multi-line comment beginning with /* and ending with */:

/* This is a
multi-line comment */
/*Best Practice
As you write code, you should regularly add comments to clarify the function of parts of your code. Good commenting can help communicate the intent of your code—both for others and for your future self.


Try creating one of each type of comment.*/

ComparisonWithTheEqualityOperator.js

/**Comparison with the Equality Operator
There are many Comparison Operators in JavaScript. All of these operators return a boolean true or false value.

The most basic operator is the equality operator ==. The equality operator compares two values and returns true if they're equivalent or false if they are not. Note that equality is different from assignment (=), which assigns the value at the right of the operator to a variable in the left.

function equalityTest(myVal) {
  if (myVal == 10) {
     return "Equal";
  }
  return "Not Equal";
}
If myVal is equal to 10, the equality operator returns true, so the code in the curly braces will execute, and the function will return "Equal". Otherwise, the function will return "Not Equal".

In order for JavaScript to compare two different data types (for example, numbers and strings), it must convert one type to another. This is known as "Type Coercion". Once it does, however, it can compare terms as follows:

1 == 1 // true
1 == 2 // false
1 == '1' // true
"3" == 3 // true

Add the equality operator to the indicated line so that the function will return "Equal" when val is equivalent to 12 */
// Setup
function testEqual(val) {
    if (val == 12) { // Change this line
      
      return "Equal";
    }
    return "Not Equal";
  }
  
  // Change this value to test
  testEqual(12);

ComparisonWithTheGreaterThanOperator.js

/**Comparison with the Greater Than Operator
The greater than operator (>) compares the values of two numbers. If the number to the left is greater than the number to the right, it returns true. Otherwise, it returns false.

Like the equality operator, greater than operator will convert data types of values while comparing.

Examples

5 > 3 // true
7 > '3' // true
2 > 3 // false
'1' > 9 // false

Add the greater than operator to the indicated lines so that the return statements make sense. */
function testGreaterThan(val) {
    if (val > 100) {  // Change this line
      return "Over 100";
    }
    
    if (val > 10) {  // Change this line
      return "Over 10";
    }
  
    return "10 or Under";
  }
  
  // Change this value to test
  testGreaterThan(10);

ComparisonWithTheGreaterThanOrEqualToOperator.js

/**Comparison with the Greater Than Or Equal To Operator
The greater than or equal to operator (>=) compares the values of two numbers. If the number to the left is greater than or equal to the number to the right, it returns true. Otherwise, it returns false.

Like the equality operator, greater than or equal to operator will convert data types while comparing.

Examples

6 >= 6 // true
7 >= '3' // true
2 >= 3 // false
'7' >= 9 // false

Add the greater than or equal to operator to the indicated lines so that the return statements make sense. */
function testGreaterOrEqual(val) {
    if (val >= 20) {  // Change this line
      return "20 or Over";
    }
    
    if (val >= 10) {  // Change this line
      return "10 or Over";
    }
  
    return "Less than 10";
  }
  
  // Change this value to test
  testGreaterOrEqual(10);

ComparisonWithTheInequalityOperator.js

/**Comparison with the Inequality Operator
The inequality operator (!=) is the opposite of the equality operator. It means "Not Equal" and returns false where equality would return true and vice versa. Like the equality operator, the inequality operator will convert data types of values while comparing.

Examples

1 != 2 // true
1 != "1" // false
1 != '1' // false
1 != true // false
0 != false // false

Add the inequality operator != in the if statement so that the function will return "Not Equal" when val is not equivalent to 99 */
// Setup
function testNotEqual(val) {
    if (val != 99) { // Change this line
      return "Not Equal";
    }
    return "Equal";
  }
  
  // Change this value to test
  testNotEqual(99);

ComparisonWithTheLessThanOperator.js

/**Comparison with the Less Than Operator
The less than operator (<) compares the values of two numbers. If the number to the left is less than the number to the right, it returns true. Otherwise, it returns false. Like the equality operator, less than operator converts data types while comparing.

Examples

2 < 5 // true
'3' < 7 // true
5 < 5 // false
3 < 2 // false
'8' < 4 // false

Add the less than operator to the indicated lines so that the return statements make sense. */
function testLessThan(val) {
    if (val <25 ) {  // Change this line
      return "Under 25";
    }
    
    if (val < 55) {  // Change this line
      return "Under 55";
    }
  
    return "55 or Over";
  }
  
  // Change this value to test
  testLessThan(10);

ComparisonWithTheLessThanOrEqualToOperator.js

/**Comparison with the Less Than Or Equal To Operator
The less than or equal to operator (<=) compares the values of two numbers. If the number to the left is less than or equal to the number to the right, it returns true. If the number on the left is greater than the number on the right, it returns false. Like the equality operator, less than or equal to converts data types.

Examples

4 <= 5 // true
'7' <= 7 // true
5 <= 5 // true
3 <= 2 // false
'8' <= 4 // false

Add the less than or equal to operator to the indicated lines so that the return statements make sense. */
function testLessOrEqual(val) {
    if (val <= 12) {  // Change this line
      return "Smaller Than or Equal to 12";
    }
    
    if (val <= 24) {  // Change this line
      return "Smaller Than or Equal to 24";
    }
  
    return "More Than 24";
  }
  
  // Change this value to test
  testLessOrEqual(10);
  

ComparisonWithTheLogicalAndOperator.js

/**Comparisons with the Logical And Operator
Sometimes you will need to test more than one thing at a time. The logical and operator (&&) returns true if and only if the operands to the left and right of it are true.

The same effect could be achieved by nesting an if statement inside another if:

if (num > 5) {
  if (num < 10) {
    return "Yes";
  }
}
return "No";
will only return "Yes" if num is greater than 5 and less than 10. The same logic can be written as:

if (num > 5 && num < 10) {
  return "Yes";
}
return "No";

Combine the two if statements into one statement which will return "Yes" if val is less than or equal to 50 and greater than or equal to 25. Otherwise, will return "No" */
function testLogicalAnd(val) {
    // Only change code below this line
  
      if (val <= 50 && val >= 25) {
        return "Yes";
      }
  
    // Only change code above this line
    return "No";
  }
  
  // Change this value to test
  testLogicalAnd(10);

ComparisonWithTheLogicalOrOperator.js

/**Comparisons with the Logical Or Operator
The logical or operator (||) returns true if either of the operands is true. Otherwise, it returns false.

The logical or operator is composed of two pipe symbols (|). This can typically be found between your Backspace and Enter keys.

The pattern below should look familiar from prior waypoints:

if (num > 10) {
  return "No";
}
if (num < 5) {
  return "No";
}
return "Yes";
will return "Yes" only if num is between 5 and 10 (5 and 10 included). The same logic can be written as:

if (num > 10 || num < 5) {
  return "No";
}
return "Yes";

Combine the two if statements into one statement which returns "Outside" if val is not between 10 and 20, inclusive. Otherwise, return "Inside". */
function testLogicalOr(val) {
    // Only change code below this line
  
    
  
    if (val < 10 || val > 20) {
      return "Outside";
    }
  
    // Only change code above this line
    return "Inside";
  }
  
  // Change this value to test
  testLogicalOr(15);

ComparisonWithTheStrictEqualityOperator.js

/**Comparison with the Strict Equality Operator
Strict equality (===) is the counterpart to the equality operator (==). However, unlike the equality operator, which attempts to convert both values being compared to a common type, the strict equality operator does not perform a type conversion.

If the values being compared have different types, they are considered unequal, and the strict equality operator will return false.

Examples

3 === 3 // true
3 === '3' // false
In the second example, 3 is a Number type and '3' is a String type.


Use the strict equality operator in the if statement so the function will return "Equal" when val is strictly equal to 7 */
// Setup
function testStrict(val) {
    if (val === 7) { // Change this line
      return "Equal";
    }
    return "Not Equal";
  }
  
  // Change this value to test
  testStrict(7);

ComparisonWithTheStrictInequalityOperator.js

/**Comparison with the Strict Inequality Operator
The strict inequality operator (!==) is the logical opposite of the strict equality operator. It means "Strictly Not Equal" and returns false where strict equality would return true and vice versa. Strict inequality will not convert data types.

Examples

3 !== 3 // false
3 !== '3' // true
4 !== 3 // true

Add the strict inequality operator to the if statement so the function will return "Not Equal" when val is not strictly equal to 17 */
// Setup
function testStrictNotEqual(val) {
    // Only Change Code Below this Line
    
    if (val !== 17) {
  
    // Only Change Code Above this Line
  
      return "Not Equal";
    }
    return "Equal";
  }
  
  // Change this value to test
  testStrictNotEqual(17);

CompoundAssignmentWithAugentedMiltiplication.js

/**Compound Assignment With Augmented Multiplication
The *= operator multiplies a variable by a number.

myVar = myVar * 5;

will multiply myVar by 5. This can be rewritten as:

myVar *= 5;


Convert the assignments for a, b, and c to use the *= operator. */
var a = 5;
var b = 12;
var c = 4.6;

// Only modify code below this line

a *= 5;
b *= b;
c *= 10;

CompoundAssignmentWithAugmentAddition.js

/**Compound Assignment With Augmented Addition
In programming, it is common to use assignments to modify the contents of a variable. Remember that everything to the right of the equals sign is evaluated first, so we can say:

myVar = myVar + 5;

to add 5 to myVar. Since this is such a common pattern, there are operators which do both a mathematical operation and assignment in one step.

One such operator is the += operator.

var myVar = 1;
myVar += 5;
console.log(myVar); // Returns 6

Convert the assignments for a, b, and c to use the += operator. */
var a = 3;
var b = 17;
var c = 12;

// Only modify code below this line

a += 12;
b += 9;
c +=7;

CompoundAssignmentWithAugmentDivision.js

/**Compound Assignment With Augmented Division
The /= operator divides a variable by another number.

myVar = myVar / 5;

Will divide myVar by 5. This can be rewritten as:

myVar /= 5;


Convert the assignments for a, b, and c to use the /= operator. */
var a = 48;
var b = 108;
var c = 33;

// Only modify code below this line

a /= 12;
b /= 4;
c /= 11;

CompoundAssignmentWithAugmentSubtraction.js

/**Compound Assignment With Augmented Subtraction
Like the += operator, -= subtracts a number from a variable.

myVar = myVar - 5;

will subtract 5 from myVar. This can be rewritten as:

myVar -= 5;


Convert the assignments for a, b, and c to use the -= operator. */
var a = 11;
var b = 9;
var c = 3;

// Only modify code below this line

a -= 6;
b -= 15;
c -= 1;

ConcatinatingStringsWithPlusOperator.js

/**Concatenating Strings with Plus Operator
In JavaScript, when the + operator is used with a String value, it is called the concatenation operator. You can build a new string out of other strings by concatenating them together.

Example

'My name is Alan,' + ' I concatenate.'
Note
Watch out for spaces. Concatenation does not add spaces between concatenated strings, so you'll need to add them yourself.


Build myStr from the strings "This is the start. " and "This is the end." using the + operator. */
// Example
var ourStr = "I come first. " + "I come second.";

// Only change code below this line

var myStr = "This is the start. " + "This is the end.";

ConcatinatingStringsWithThePlusEqualsOperator.js

/**Concatenating Strings with the Plus Equals Operator
We can also use the += operator to concatenate a string onto the end of an existing string variable. This can be very helpful to break a long string over several lines.

Note
Watch out for spaces. Concatenation does not add spaces between concatenated strings, so you'll need to add them yourself.


Build myStr over several lines by concatenating these two strings: "This is the first sentence. " and "This is the second sentence." using the += operator. Use the += operator similar to how it is shown in the editor. Start by assigning the first string to myStr, then add on the second string. */
// Example
var ourStr = "I come first. ";
ourStr += "I come second.";

// Only change code below this line

var myStr = "This is the first sentence. ";
myStr += "This is the second sentence.";

ConstructingStringsWithVariables.js

/**Constructing Strings with Variables
Sometimes you will need to build a string, Mad Libs style. By using the concatenation operator (+), you can insert one or more variables into a string you're building.


Set myName to a string equal to your name and build myStr with myName between the strings "My name is " and " and I am well!" */
// Example
var ourName = "freeCodeCamp";
var ourStr = "Hello, our name is " + ourName + ", how are you?";

// Only change code below this line
var myName = "Anna";
var myStr = "My name is " + myName + " and I am well!";

CountBackwardsWithaForLoop.js

/**Count Backwards With a For Loop
A for loop can also count backwards, so long as we can define the right conditions.

In order to count backwards by twos, we'll need to change our initialization, condition, and final-expression.

We'll start at i = 10 and loop while i > 0. We'll decrement i by 2 each loop with i -= 2.

var ourArray = [];
for (var i=10; i > 0; i-=2) {
  ourArray.push(i);
}
ourArray will now contain [10,8,6,4,2].

Let's change our initialization and final-expression so we can count backward by twos by odd numbers.


Push the odd numbers from 9 through 1 to myArray using a for loop. */

// Example
var ourArray = [];

for (var i = 10; i > 0; i -= 2) {
  ourArray.push(i);
}

// Setup
var myArray = [];

for (var i = 9; i > 0; i -= 2 ){
  myArray.push(i);
}
// Only change code below this line.

countingCards.js

/**Counting Cards
In the casino game Blackjack, a player can gain an advantage over the house by keeping track of the relative number of high and low cards remaining in the deck. This is called Card Counting.

Having more high cards remaining in the deck favors the player. Each card is assigned a value according to the table below. When the count is positive, the player should bet high. When the count is zero or negative, the player should bet low.

Count Change	Cards
+1	2, 3, 4, 5, 6
0	7, 8, 9
-1	10, 'J', 'Q', 'K', 'A'
You will write a card counting function. It will receive a card parameter, which can be a number or a string, and increment or decrement the global count variable according to the card's value (see table). The function will then return a string with the current count and the string Bet if the count is positive, or Hold if the count is zero or negative. The current count and the player's decision (Bet or Hold) should be separated by a single space.

Example Output
-3 Hold
5 Bet

Hint
Do NOT reset count to 0 when value is 7, 8, or 9.
Do NOT return an array.
Do NOT include quotes (single or double) in the output. */
var count = 0;

function cc(card) {
      // Only change code below this line
      switch(card){
        case 2:
        case 3:
        case 4:
        case 5:
        case 6:
          count++;
          break;
        case 10:
        case "J":
        case "Q":
        case "K":
        case "A":
          count--;
          break;
      }
      if (count > 0){
        return count + " Bet";
      } else {
        return count + " Hold";
      }
      // Only change code above this line
    }

// Add/remove calls to test your function.
// Note: Only the last will display
cc(2); cc(3); cc(7); cc('K'); cc('A');

CreateDecimalNumbersWithJavaScript.js

/**Create Decimal Numbers with JavaScript
We can store decimal numbers in variables too. Decimal numbers are sometimes referred to as floating point numbers or floats.

Note
Not all real numbers can accurately be represented in floating point. This can lead to rounding errors. Details Here.


Create a variable myDecimal and give it a decimal value with a fractional part (e.g. 5.7). */
var ourDecimal = 5.7;

// Only change code below this line

var myDecimal = 2.2;

DeclareJavaScriptVariables.js

/**Declare JavaScript Variables
In computer science, data is anything that is meaningful to the computer. JavaScript provides seven different data types which are undefined, null, boolean, string, symbol, number, and object.

For example, computers distinguish between numbers, such as the number 12, and strings, such as "12", "dog", or "123 cats", which are collections of characters. Computers can perform mathematical operations on a number, but not on a string.

Variables allow computers to store and manipulate data in a dynamic fashion. They do this by using a "label" to point to the data rather than using the data itself. Any of the seven data types may be stored in a variable.

Variables are similar to the x and y variables you use in mathematics, which means they're a simple name to represent the data we want to refer to. Computer variables differ from mathematical variables in that they can store different values at different times.

We tell JavaScript to create or declare a variable by putting the keyword var in front of it, like so:

var ourName;
creates a variable called ourName. In JavaScript we end statements with semicolons.

Variable names can be made up of numbers, letters, and $ or _, but may not contain spaces or start with a number.


Use the var keyword to create a variable called myName.

Hint
Look at the ourName example if you get stuck. */
// Example
var ourName;
var myName;
// Declare myName below this line

DecrementANumberWithJavaScript.js

/**Decrement a Number with JavaScript
You can easily decrement or decrease a variable by one with the -- operator.

i--;

is the equivalent of

i = i - 1;

Note
The entire line becomes i--;, eliminating the need for the equal sign.


Change the code to use the -- operator on myVar. */
var myVar = 11;

// Only change code below this line
myVar --;

DeletePropertiesFromAJavaScriptObject.js

/**Delete Properties from a JavaScript Object
We can also delete properties from objects like this:

delete ourDog.bark;


Delete the "tails" property from myDog. You may use either dot or bracket notation. */
// Example
var ourDog = {
    "name": "Camper",
    "legs": 4,
    "tails": 1,
    "friends": ["everything!"],
    "bark": "bow-wow"
  };
  
  delete ourDog.bark;
  
  // Setup
  var myDog = {
    "name": "Happy Coder",
    "legs": 4,
    "tails": 1,
    "friends": ["freeCodeCamp Campers"],
    "bark": "woof"
  };
  
  delete myDog["tails"];
  // Only change code below this line.
  

DivideOneDecimalByAnotherWithJavaScript.js

/**Divide One Decimal by Another with JavaScript
Now let's divide one decimal by another.


Change the 0.0 so that quotient will equal to 2.2. */
var quotient = 4.4 / 2.0; // Fix this line

DivideOneNumberByAnotherWithJavaScript.js

/**Divide One Number by Another with JavaScript
We can also divide one number by another.

JavaScript uses the / symbol for division.

Example

myVar = 16 / 2; // assigned 8

Change the 0 so that the quotient is equal to 2. */
var quotient = 66 / 33;

EscapeSentencesInStrungs.js

/**Escape Sequences in Strings
Quotes are not the only characters that can be escaped inside a string. There are two reasons to use escaping characters: First is to allow you to use characters you might not otherwise be able to type out, such as a backspace. Second is to allow you to represent multiple quotes in a string without JavaScript misinterpreting what you mean. We learned this in the previous challenge.

Code	Output
\'	single quote
\"	double quote
\\	backslash
\n	newline
\r	carriage return
\t	tab
\b	backspace
\f	form feed
Note that the backslash itself must be escaped in order to display as a backslash.


Assign the following three lines of text into the single variable myStr using escape sequences.

FirstLine
    \SecondLine
ThirdLine
You will need to use escape sequences to insert special characters correctly. You will also need to follow the spacing as it looks above, with no spaces between escape sequences or words.

Here is the text with the escape sequences written out.

FirstLinenewlinetabbackslashSecondLinenewlineThirdLine */

var myStr = "FirstLine\n\t\bSecondLine\nThirdLine"; // Change this line

EscapingLiteralQuotesInStrings.js

/**Escaping Literal Quotes in Strings
When you are defining a string you must start and end with a single or double quote. What happens when you need a literal quote: " or ' inside of your string?

In JavaScript, you can escape a quote from considering it as an end of string quote by placing a backslash (\) in front of the quote.

var sampleStr = "Alan said, \"Peter is learning JavaScript\".";

This signals to JavaScript that the following quote is not the end of the string, but should instead appear inside the string. So if you were to print this to the console, you would get:

Alan said, "Peter is learning JavaScript".


Use backslashes to assign a string to the myStr variable so that if you were to print it to the console, you would see:

I am a "double quoted" string inside "double quotes". */
var myStr = "I am a \"double quoted\" string inside \"double quotes\"."; // Change this line

FindingARemainderInJavaScript.js

/**Finding a Remainder in JavaScript
The remainder operator % gives the remainder of the division of two numbers.

Example

5 % 2 = 1 because
Math.floor(5 / 2) = 2 (Quotient)
2 * 2 = 4
5 - 4 = 1 (Remainder)
Usage
In mathematics, a number can be checked to be even or odd by checking the remainder of the division of the number by 2.

17 % 2 = 1 (17 is Odd)
48 % 2 = 0 (48 is Even)
Note
The remainder operator is sometimes incorrectly referred to as the "modulus" operator. It is very similar to modulus, but does not work properly with negative numbers.


Set remainder equal to the remainder of 11 divided by 3 using the remainder (%) operator. */
// Only change code below this line

var remainder;
remainder = 11 % 3;

FindTheLengthOfAString.js

/**Find the Length of a String
You can find the length of a String value by writing .length after the string variable or string literal.

"Alan Peter".length; // 10

For example, if we created a variable var firstName = "Charles", we could find out how long the string "Charles" is by using the firstName.length property.


Use the .length property to count the number of characters in the lastName variable and assign it to lastNameLength. */
// Example
var firstNameLength = 0;
var firstName = "Ada";

firstNameLength = firstName.length;

// Setup
var lastNameLength = 0;
var lastName = "Lovelace";

// Only change code below this line.

lastNameLength = lastName.length;

generateRandomFractionsWithJavaScript.js

/**Generate Random Fractions with JavaScript
Random numbers are useful for creating random behavior.

JavaScript has a Math.random() function that generates a random decimal number between 0 (inclusive) and not quite up to 1 (exclusive). Thus Math.random() can return a 0 but never quite return a 1

Note
Like Storing Values with the Equal Operator, all function calls will be resolved before the return executes, so we can return the value of the Math.random() function.


Change randomFraction to return a random number instead of returning 0. */

function randomFraction() {

    // Only change code below this line.
  
    return Math.random();
  
    // Only change code above this line.
  }

GenerateRandomWholeNumbersWithinaRange.js

/**Generate Random Whole Numbers within a Range
Instead of generating a random number between zero and a given number like we did before, we can generate a random number that falls within a range of two specific numbers.

To do this, we'll define a minimum number min and a maximum number max.

Here's the formula we'll use. Take a moment to read it and try to understand what this code is doing:

Math.floor(Math.random() * (max - min + 1)) + min


Create a function called randomRange that takes a range myMin and myMax and returns a random number that's greater than or equal to myMin, and is less than or equal to myMax, inclusive. */
// Example
function ourRandomRange(ourMin, ourMax) {

    return Math.floor(Math.random() * (ourMax - ourMin + 1)) + ourMin;
  }
  
  ourRandomRange(1, 9);
  
  // Only change code below this line.
  
  function randomRange(myMin, myMax) {
  
    return Math.floor(Math.random() * (myMax - myMin + 1)) + myMin; // Change this line
  
  }
  
  // Change these values to test your function
  var myRandom = randomRange(5, 15);

generateRandomWholeNumberswithJavaScript.js

/**Generate Random Whole Numbers with JavaScript
It's great that we can generate random decimal numbers, but it's even more useful if we use it to generate random whole numbers.

Use Math.random() to generate a random decimal.
Multiply that random decimal by 20.
Use another function, Math.floor() to round the number down to its nearest whole number.
Remember that Math.random() can never quite return a 1 and, because we're rounding down, it's impossible to actually get 20. This technique will give us a whole number between 0 and 19.

Putting everything together, this is what our code looks like:

Math.floor(Math.random() * 20);

We are calling Math.random(), multiplying the result by 20, then passing the value to Math.floor() function to round the value down to the nearest whole number.


Use this technique to generate and return a random whole number between 0 and 9. */
var randomNumberBetween0and19 = Math.floor(Math.random() * 20);

function randomWholeNum() {

  // Only change code below this line.
  var rand = Math.floor(Math.random() * 10);
  return rand;
}

GlobalScopeAndFunctions.js

/**Global Scope and Functions
In JavaScript, scope refers to the visibility of variables. Variables which are defined outside of a function block have Global scope. This means, they can be seen everywhere in your JavaScript code.

Variables which are used without the var keyword are automatically created in the global scope. This can create unintended consequences elsewhere in your code or when running a function again. You should always declare your variables with var.


Using var, declare a global variable myGlobal outside of any function. Initialize it with a value of 10.

Inside function fun1, assign 5 to oopsGlobal without using the var keyword. */
// Declare your variable here
var myGlobal = 10;

function fun1() {
  // Assign 5 to oopsGlobal Here
  oopsGlobal = 5;
}

// Only change code above this line
function fun2() {
  var output = "";
  if (typeof myGlobal != "undefined") {
    output += "myGlobal: " + myGlobal;
  }
  if (typeof oopsGlobal != "undefined") {
    output += " oopsGlobal: " + oopsGlobal;
  }
  console.log(output);
}

GolfCode.js

/**Golf Code
In the game of golf each hole has a par meaning the average number of strokes a golfer is expected to make in order to sink the ball in a hole to complete the play. Depending on how far above or below par your strokes are, there is a different nickname.

Your function will be passed par and strokes arguments. Return the correct string according to this table which lists the strokes in order of priority; top (highest) to bottom (lowest):

Strokes	Return
1	"Hole-in-one!"
<= par - 2	"Eagle"
par - 1	"Birdie"
par	"Par"
par + 1	"Bogey"
par + 2	"Double Bogey"
>= par + 3	"Go Home!"
par and strokes will always be numeric and positive. We have added an array of all the names for your convenience. */
var names = ["Hole-in-one!", "Eagle", "Birdie", "Par", "Bogey", "Double Bogey", "Go Home!"];
function golfScore(par, strokes) {
  // Only change code below this line
  if (strokes === 1) {
    return "Hole-in-one!";
  } else if ( strokes <= par-2) {
    return "Eagle";
  } else if (strokes == par-1) {
    return "Birdie";
  } else if (strokes === par) {
    return "Par";
  } else if (strokes == par+1) {
    return "Bogey";
  } else if (strokes == par+2) {
    return "Double Bogey";
  } else if (strokes >=par+3) {
    return "Go Home!";
  }
  
  return "Change Me";
  // Only change code above this line
}

// Change these values to test
golfScore(5, 4);

IncrementANumberWithJavaScript.js

/**Increment a Number with JavaScript
You can easily increment or add one to a variable with the ++ operator.

i++;

is the equivalent of

i = i + 1;

Note
The entire line becomes i++;, eliminating the need for the equal sign.


Change the code to use the ++ operator on myVar.

Hint
Learn more about Arithmetic operators - Increment (++). */
var myVar = 87;

// Only change code below this line
myVar ++;

InitializingVariablesWithTheAssignmentOperator.js

/**Initializing Variables with the Assignment Operator
It is common to initialize a variable to an initial value in the same line as it is declared.

var myVar = 0;

Creates a new variable called myVar and assigns it an initial value of 0.


Define a variable a with var and initialize it to a value of 9. */
// Example
var ourVar = 19;
var a = 9;
// Only change code below this line

IntroducingElseStatements.js

/**Introducing Else Statements
When a condition for an if statement is true, the block of code following it is executed. What about when that condition is false? Normally nothing would happen. With an else statement, an alternate block of code can be executed.

if (num > 10) {
  return "Bigger than 10";
} else {
  return "10 or Less";
}

Combine the if statements into a single if/else statement. */
function testElse(val) {
    var result = "";
    // Only change code below this line
    
    if (val > 5) {
      result = "Bigger than 5";
    }
    
    else  {
      result = "5 or Smaller";
    }
  
    
    // Only change code above this line
    return result;
  }
  
  // Change this value to test
  testElse(4);
  

IterateOddNumbersWithAForLoop.js

/**Iterate Odd Numbers With a For Loop
For loops don't have to iterate one at a time. By changing our final-expression, we can count by even numbers.

We'll start at i = 0 and loop while i < 10. We'll increment i by 2 each loop with i += 2.

var ourArray = [];
for (var i = 0; i < 10; i += 2) {
  ourArray.push(i);
}
ourArray will now contain [0,2,4,6,8].

Let's change our initialization so we can count by odd numbers.


Push the odd numbers from 1 through 9 to myArray using a for loop. */

// Example
var ourArray = [];

for (var i = 0; i < 10; i += 2) {
  ourArray.push(i);
}

// Setup
var myArray = [];

for (var i = 1 ; i < 10; i+=2){
  myArray.push(i);
}
// Only change code below this line.

iterateThroughAnArrayWithaForLoop.js

/**Iterate Through an Array with a For Loop
A common task in JavaScript is to iterate through the contents of an array. One way to do that is with a for loop. This code will output each element of the array arr to the console:

var arr = [10,9,8,7,6];
for (var i = 0; i < arr.length; i++) {
   console.log(arr[i]);
}
Remember that Arrays have zero-based numbering, which means the last index of the array is length - 1. Our condition for this loop is i < arr.length, which stops when i is at length - 1.


Declare and initialize a variable total to 0. Use a for loop to add the value of each element of the myArr array to total. */

// Example
var ourArr = [ 9, 10, 11, 12];
var ourTotal = 0;

for (var i = 0; i < ourArr.length; i++) {
  ourTotal += ourArr[i];
}

// Setup
var myArr = [ 2, 3, 4, 5, 6];

var total =0;
for(var i = 0; i < myArr.length; i++){
  total += myArr[i];
}
// Only change code below this line

iterateWithJavaScriptDoWhileLoops.js

/**Iterate with JavaScript Do...While Loops
You can run the same code multiple times by using a loop.

The next type of loop you will learn is called a "do...while" loop because it first will "do" one pass of the code inside the loop no matter what, and then it runs "while" a specified condition is true and stops once that condition is no longer true. Let's look at an example.

var ourArray = [];
var i = 0;
do {
  ourArray.push(i);
  i++;
} while (i < 5);
This behaves just as you would expect with any other type of loop, and the resulting array will look like [0, 1, 2, 3, 4]. However, what makes the do...while different from other loops is how it behaves when the condition fails on the first check. Let's see this in action.

Here is a regular while loop that will run the code in the loop as long as i < 5.

var ourArray = []; 
var i = 5;
while (i < 5) {
  ourArray.push(i);
  i++;
}
Notice that we initialize the value of i to be 5. When we execute the next line, we notice that i is not less than 5. So we do not execute the code inside the loop. The result is that ourArray will end up with nothing added to it, so it will still look like this [] when all the code in the example above finishes running.

Now, take a look at a do...while loop.

var ourArray = []; 
var i = 5;
do {
  ourArray.push(i);
  i++;
} while (i < 5);
In this case, we initialize the value of i as 5, just like we did with the while loop. When we get to the next line, there is no check for the value of i, so we go to the code inside the curly braces and execute it. We will add one element to the array and increment i before we get to the condition check. Then, when we get to checking if i < 5 see that i is now 6, which fails the conditional check. So we exit the loop and are done. At the end of the above example, the value of ourArray is [5].

Essentially, a do...while loop ensures that the code inside the loop will run at least once.

Let's try getting a do...while loop to work by pushing values to an array.


Change the while loop in the code to a do...while loop so that the loop will push the number 10 to myArray, and i will be equal to 11 when your code finishes running. */
// Setup
var myArray = [];
var i = 10;

// Only change code below this line.
do {
  myArray.push(i);
  i++;
}
while (i != 11) ;

iterateWithJavaScriptForLoops.js

/**Iterate with JavaScript For Loops
You can run the same code multiple times by using a loop.

The most common type of JavaScript loop is called a "for loop" because it runs "for" a specific number of times.

For loops are declared with three optional expressions separated by semicolons:

for ([initialization]; [condition]; [final-expression])

The initialization statement is executed one time only before the loop starts. It is typically used to define and setup your loop variable.

The condition statement is evaluated at the beginning of every loop iteration and will continue as long as it evaluates to true. When condition is false at the start of the iteration, the loop will stop executing. This means if condition starts as false, your loop will never execute.

The final-expression is executed at the end of each loop iteration, prior to the next condition check and is usually used to increment or decrement your loop counter.

In the following example we initialize with i = 0 and iterate while our condition i < 5 is true. We'll increment i by 1 in each loop iteration with i++ as our final-expression.

var ourArray = [];
for (var i = 0; i < 5; i++) {
  ourArray.push(i);
}
ourArray will now contain [0,1,2,3,4].


Use a for loop to work to push the values 1 through 5 onto myArray. */
// Example
var ourArray = [];

for (var i = 0; i < 5; i++) {
  ourArray.push(i);
}

// Setup
var myArray = [];

for(var i = 1 ; i <= 5 ; i++){
    myArray.push(i);
}

// Only change code below this line.

iterateWithJavaScriptWhileLoops.js

/**Iterate with JavaScript While Loops
You can run the same code multiple times by using a loop.

The first type of loop we will learn is called a "while" loop because it runs "while" a specified condition is true and stops once that condition is no longer true.

var ourArray = [];
var i = 0;
while(i < 5) {
  ourArray.push(i);
  i++;
}
Let's try getting a while loop to work by pushing values to an array.


Push the numbers 0 through 4 to myArray using a while loop */
// Setup
var myArray = [];
var i = 0;
while(i <= 4) {
  myArray.push(i);
  i++;
}
// Only change code below this line.

LogicalOrderInIfElseStatements.js

/**Logical Order in If Else Statements
Order is important in if, else if statements.

The function is executed from top to bottom so you will want to be careful of what statement comes first.

Take these two functions as an example.

Here's the first:

function foo(x) {
  if (x < 1) {
    return "Less than one";
  } else if (x < 2) {
    return "Less than two";
  } else {
    return "Greater than or equal to two";
  }
}
And the second just switches the order of the statements:

function bar(x) {
  if (x < 2) {
    return "Less than two";
  } else if (x < 1) {
    return "Less than one";
  } else {
    return "Greater than or equal to two";
  }
}
While these two functions look nearly identical if we pass a number to both we get different outputs.

foo(0) // "Less than one"
bar(0) // "Less than two"

Change the order of logic in the function so that it will return the correct statements in all cases. */

function orderMyLogic(val) {
    if (val < 5) {
      return "Less than 5";
    } else if (val < 10) {
      return "Less than 10";
    } else {
      return "Greater than or equal to 10";
    }
  }
  
  // Change this value to test
  orderMyLogic(7);

ManipilateArraysWithShift.js

/**Manipulate Arrays With shift()
pop() always removes the last element of an array. What if you want to remove the first?

That's where .shift() comes in. It works just like .pop(), except it removes the first element instead of the last.


Use the .shift() function to remove the first item from myArray, assigning the "shifted off" value to removedFromMyArray. */
// Example
var ourArray = ["Stimpson", "J", ["cat"]];
var removedFromOurArray = ourArray.shift();
// removedFromOurArray now equals "Stimpson" and ourArray now equals ["J", ["cat"]].

// Setup
var myArray = [["John", 23], ["dog", 3]];

// Only change code below this line.
var removedFromMyArray = myArray.shift();

ManipulateArraysWithPush.js

/**Manipulate Arrays With push()
An easy way to append data to the end of an array is via the push() function.

.push() takes one or more parameters and "pushes" them onto the end of the array.

var arr = [1,2,3];
arr.push(4);
// arr is now [1,2,3,4]

Push ["dog", 3] onto the end of the myArray variable. */
// Example
var ourArray = ["Stimpson", "J", "cat"];
ourArray.push(["happy", "joy"]); 
// ourArray now equals ["Stimpson", "J", "cat", ["happy", "joy"]]

// Setup
var myArray = [["John", 23], ["cat", 2]];
myArray.push(["dog", 3]);

// Only change code below this line.

ManipulateArraysWithUnshift.js

/**Manipulate Arrays With unshift()
Not only can you shift elements off of the beginning of an array, you can also unshift elements to the beginning of an array i.e. add elements in front of the array.

.unshift() works exactly like .push(), but instead of adding the element at the end of the array, unshift() adds the element at the beginning of the array.


Add ["Paul",35] to the beginning of the myArray variable using unshift(). */
// Example
var ourArray = ["Stimpson", "J", "cat"];
ourArray.shift(); // ourArray now equals ["J", "cat"]
ourArray.unshift("Happy"); 
// ourArray now equals ["Happy", "J", "cat"]

// Setup
var myArray = [["John", 23], ["dog", 3]];
myArray.shift();
myArray.unshift(["Paul", 35]);

// Only change code below this line.

ManipulateArrayWithPop.js

/**Manipulate Arrays With pop()
Another way to change the data in an array is with the .pop() function.

.pop() is used to "pop" a value off of the end of an array. We can store this "popped off" value by assigning it to a variable. In other words, .pop() removes the last element from an array and returns that element.

Any type of entry can be "popped" off of an array - numbers, strings, even nested arrays.

var threeArr = [1, 4, 6];
var oneDown = threeArr.pop();
console.log(oneDown); // Returns 6
console.log(threeArr); // Returns [1, 4]

Use the .pop() function to remove the last item from myArray, assigning the "popped off" value to removedFromMyArray. */
// Example
var ourArray = [1,2,3];
var removedFromOurArray = ourArray.pop(); 
// removedFromOurArray now equals 3, and ourArray now equals [1,2]

// Setup
var myArray = [["John", 23], ["cat", 2]];

// Only change code below this line.
var removedFromMyArray = myArray.pop();

ManipulatingComplexObjects.js

/**Manipulating Complex Objects
Sometimes you may want to store data in a flexible Data Structure. A JavaScript object is one way to handle flexible data. They allow for arbitrary combinations of strings, numbers, booleans, arrays, functions, and objects.

Here's an example of a complex data structure:

var ourMusic = [
  {
    "artist": "Daft Punk",
    "title": "Homework",
    "release_year": 1997,
    "formats": [ 
      "CD", 
      "Cassette", 
      "LP"
    ],
    "gold": true
  }
];
This is an array which contains one object inside. The object has various pieces of metadata about an album. It also has a nested "formats" array. If you want to add more album records, you can do this by adding records to the top level array.

Objects hold data in a property, which has a key-value format. In the example above, "artist": "Daft Punk" is a property that has a key of "artist" and a value of "Daft Punk".

JavaScript Object Notation or JSON is a related data interchange format used to store data.

{
  "artist": "Daft Punk",
  "title": "Homework",
  "release_year": 1997,
  "formats": [ 
    "CD",
    "Cassette",
    "LP"
  ],
  "gold": true
}
Note
You will need to place a comma after every object in the array, unless it is the last object in the array.


Add a new album to the myMusic array. Add artist and title strings, release_year number, and a formats array of strings. */
var myMusic = [
    {
      "artist": "Billy Joel",
      "title": "Piano Man",
      "release_year": 1973,
      "formats": [ 
        "CD",
        "8T",
        "LP"
      ],
      "gold": true
    },
    // Add record here
    {
      "artist": "Billy Joel",
      "title": "Piano Man",
      "release_year": 1973,
      "formats": [ 
        "CD",
        "8T",
        "LP"
      ]
    }
  ];

ModifyArrayDataWithIndexes.js

/**Modify Array Data With Indexes
Unlike strings, the entries of arrays are mutable and can be changed freely.

Example

var ourArray = [50,40,30];
ourArray[0] = 15; // equals [15,40,30]
Note
There shouldn't be any spaces between the array name and the square brackets, like array [0]. Although JavaScript is able to process this correctly, this may confuse other programmers reading your code.


Modify the data stored at index 0 of myArray to a value of 45 */
// Example
var ourArray = [18,64,99];
ourArray[1] = 45; // ourArray now equals [18,45,99].

// Setup
var myArray = [18,64,99];
myArray[0] = 45;
// Only change code below this line.

MultipleIdenticalOptionsInSwitchStatements.js

/**Multiple Identical Options in Switch Statements
If the break statement is omitted from a switch statement's case, the following case statement(s) are executed until a break is encountered. If you have multiple inputs with the same output, you can represent them in a switch statement like this:

switch(val) {
  case 1:
  case 2:
  case 3:
    result = "1, 2, or 3";
    break;
  case 4:
    result = "4 alone";
}
Cases for 1, 2, and 3 will all produce the same result.


Write a switch statement to set answer for the following ranges:
1-3 - "Low"
4-6 - "Mid"
7-9 - "High"

Note
You will need to have a case statement for each number in the range. */
function sequentialSizes(val) {
    var answer = "";
    // Only change code below this line
    switch (val){
    case 1:
    case 2:
    case 3:
    answer = "Low";
    break;
    case 4:
    case 5:
    case 6:
    answer = "Mid";
    break;
    case 7:
    case 8:
    case 9:
    answer = "High";
    }
    
    
    
    // Only change code above this line  
    return answer;  
  }
  
  // Change this value to test
  sequentialSizes(1);
  

MultiplyTwoDecimalsWithJavaScript.js

/**Multiply Two Decimals with JavaScript
In JavaScript, you can also perform calculations with decimal numbers, just like whole numbers.

Let's multiply two decimals together to get their product.


Change the 0.0 so that product will equal 5.0. */
var product = 2.0 * 2.5;

MultiplyTwoNumbersWithJavaScript.js

/**Multiply Two Numbers with JavaScript
We can also multiply one number by another.

JavaScript uses the * symbol for multiplication of two numbers.

Example

myVar = 13 * 13; // assigned 169

Change the 0 so that product will equal 80. */
var product = 8 * 10;

NestingForLoops.js

/**Nesting For Loops
If you have a multi-dimensional array, you can use the same logic as the prior waypoint to loop through both the array and any sub-arrays. Here is an example:

var arr = [
  [1,2], [3,4], [5,6]
];
for (var i=0; i < arr.length; i++) {
  for (var j=0; j < arr[i].length; j++) {
    console.log(arr[i][j]);
  }
}
This outputs each sub-element in arr one at a time. Note that for the inner loop, we are checking the .length of arr[i], since arr[i] is itself an array.


Modify function multiplyAll so that it multiplies the product variable by each number in the sub-arrays of arr */
function multiplyAll(arr) {
    var product = 1;
    // Only change code below this line
    for (var i=0; i < arr.length; i++) {
    for (var j=0; j < arr[i].length; j++){
        product = product * arr[i][j];
      }
    }
    // Only change code above this line
    return product;
  }
  
  // Modify values below to test your code
  multiplyAll([[1,2],[3,4],[5,6,7]]);

NestOneArrayWithinAnotherArray.js

/**Nest one Array within Another Array
You can also nest arrays within other arrays, like this: [["Bulls", 23], ["White Sox", 45]]. This is also called a Multi-dimensional Array.


Create a nested array called myArray. */
// Example
var ourArray = [["the universe", 42], ["everything", 101010]];

// Only change code below this line.
var myArray = [["cat", 4], ["human", 2]];

PassingValuesToFunctionsWithArguments.js

/**Passing Values to Functions with Arguments
Parameters are variables that act as placeholders for the values that are to be input to a function when it is called. When a function is defined, it is typically defined along with one or more parameters. The actual values that are input (or "passed") into a function when it is called are known as arguments.

Here is a function with two parameters, param1 and param2:

function testFun(param1, param2) {
  console.log(param1, param2);
}
Then we can call testFun:

testFun("Hello", "World");

We have passed two arguments, "Hello" and "World". Inside the function, param1 will equal "Hello" and param2 will equal "World". Note that you could call testFun again with different arguments and the parameters would take on the value of the new arguments.


Create a function called functionWithArgs that accepts two arguments and outputs their sum to the dev console.
Call the function with two numbers as arguments. */
// Example
function ourFunctionWithArgs(a, b) {
    console.log(a - b);
  }
  ourFunctionWithArgs(10, 5); // Outputs 5
  
  // Only change code below this line.
  function functionWithArgs(arg1, arg2) {
    console.log(arg1 + arg2);
  }
  
  functionWithArgs (11, 23);
  

PracticeComparingDifferentValues.js

/**Practice comparing different values
In the last two challenges, we learned about the equality operator (==) and the strict equality operator (===). Let's do a quick review and practice using these operators some more.

If the values being compared are not of the same type, the equality operator will perform a type conversion, and then evaluate the values. However, the strict equality operator will compare both the data type and value as-is, without converting one type to the other.

Examples

3 == '3' // returns true because JavaScript performs type conversion from string to number
3 === '3' // returns false because the types are different and type conversion is not performed
Note
In JavaScript, you can determine the type of a variable or a value with the typeof operator, as follows:

typeof 3 // returns 'number'
typeof '3' // returns 'string'

The compareEquality function in the editor compares two values using the equality operator. Modify the function so that it returns "Equal" only when the values are strictly equal. */
// Setup
function compareEquality(a, b) {
    if (a === b) { // Change this line
      return "Equal";
    }
    return "Not Equal";
  }
  
  // Change this value to test
  compareEquality(10, "10");

profileLookup.js

/**Profile Lookup
We have an array of objects representing different people in our contacts lists.

A lookUpProfile function that takes name and a property (prop) as arguments has been pre-written for you.

The function should check if name is an actual contact's firstName and the given property (prop) is a property of that contact.

If both are true, then return the "value" of that property.

If name does not correspond to any contacts then return "No such contact"

If prop does not correspond to any valid properties of a contact found to match name then return "No such property" */
//Setup
var contacts = [
    {
        "firstName": "Akira",
        "lastName": "Laine",
        "number": "0543236543",
        "likes": ["Pizza", "Coding", "Brownie Points"]
    },
    {
        "firstName": "Harry",
        "lastName": "Potter",
        "number": "0994372684",
        "likes": ["Hogwarts", "Magic", "Hagrid"]
    },
    {
        "firstName": "Sherlock",
        "lastName": "Holmes",
        "number": "0487345643",
        "likes": ["Intriguing Cases", "Violin"]
    },
    {
        "firstName": "Kristian",
        "lastName": "Vos",
        "number": "unknown",
        "likes": ["JavaScript", "Gaming", "Foxes"]
    }
];


function lookUpProfile(name, prop){
// Only change code below this line
for (var x = 0; x < contacts.length; x++){
    if (contacts[x].firstName === name) {
        if (contacts[x].hasOwnProperty(prop)) {
            return contacts[x][prop];
        } else {
            return "No such property";
        }
    }
}
return "No such contact";
// Only change code above this line
}

// Change these values to test your function
lookUpProfile("Akira", "likes");

QuotingStringsWithSingleQuotes.js

/**Quoting Strings with Single Quotes
String values in JavaScript may be written with single or double quotes, as long as you start and end with the same type of quote. Unlike some other programming languages, single and double quotes work the same in JavaScript.

doubleQuoteStr = "This is a string"; 
singleQuoteStr = 'This is also a string';
The reason why you might want to use one type of quote over the other is if you want to use both in a string. This might happen if you want to save a conversation in a string and have the conversation in quotes. Another use for it would be saving an <a> tag with various attributes in quotes, all within a string.

conversation = 'Finn exclaims to Jake, "Algebraic!"';
However, this becomes a problem if you need to use the outermost quotes within it. Remember, a string has the same kind of quote at the beginning and end. But if you have that same quote somewhere in the middle, the string will stop early and throw an error.

goodStr = 'Jake asks Finn, "Hey, let\'s go on an adventure?"'; 
badStr = 'Finn responds, "Let's go!"'; // Throws an error
In the goodStr above, you can use both quotes safely by using the backslash \ as an escape character.

Note
The backslash \ should not be be confused with the forward slash /. They do not do the same thing.


Change the provided string to a string with single quotes at the beginning and end and no escape characters.

Right now, the <a> tag in the string uses double quotes everywhere. You will need to change the outer quotes to single quotes so you can remove the escape characters. */

var myStr = '<a href="http://www.example.com" target="_blank">Link</a>';

recoedCollection.js

/**Record Collection
You are given a JSON object representing a part of your musical album collection. Each album has several properties and a unique id number as its key. Not all albums have complete information.

Write a function which takes an album's id (like 2548), a property prop (like "artist" or "tracks"), and a value (like "Addicted to Love") to modify the data in this collection.

If prop isn't "tracks" and value isn't empty (""), update or set the value for that record album's property.

Your function must always return the entire collection object.

There are several rules for handling incomplete data:

If prop is "tracks" but the album doesn't have a "tracks" property, create an empty array before adding the new value to the album's corresponding property.

If prop is "tracks" and value isn't empty (""), push the value onto the end of the album's existing tracks array.

If value is empty (""), delete the given prop property from the album.

Hints
Use bracket notation when accessing object properties with variables.

Push is an array method you can read about on Mozilla Developer Network.

You may refer back to Manipulating Complex Objects Introducing JavaScript Object Notation (JSON) for a refresher. */
// Setup
var collection = {
    "2548": {
      "album": "Slippery When Wet",
      "artist": "Bon Jovi",
      "tracks": [ 
        "Let It Rock", 
        "You Give Love a Bad Name" 
      ]
    },
    "2468": {
      "album": "1999",
      "artist": "Prince",
      "tracks": [ 
        "1999", 
        "Little Red Corvette" 
      ]
    },
    "1245": {
      "artist": "Robert Palmer",
      "tracks": [ ]
    },
    "5439": {
      "album": "ABBA Gold"
    }
};
// Keep a copy of the collection for tests
var collectionCopy = JSON.parse(JSON.stringify(collection));

// Only change code below this line
function updateRecords(id, prop, value) {
  if (prop === "tracks" && value !== "") {
   if(collection[id][prop]) {
    collection[id][prop].push(value);
   }
   else {
    collection[id][prop]=[value];
   }
  } else if (value !== "") {
    collection[id][prop] = value;
  } else {
    delete collection[id][prop];
  }

  return collection;
}
// Alter values below to test your code
updateRecords(5439, "artist", "ABBA");

ReplacingIfElseChainsWithSwitch.js

/**Replacing If Else Chains with Switch
If you have many options to choose from, a switch statement can be easier to write than many chained if/else if statements. The following:

if (val === 1) {
  answer = "a";
} else if (val === 2) {
  answer = "b";
} else {
  answer = "c";
}
can be replaced with:

switch(val) {
  case 1:
    answer = "a";
    break;
  case 2:
    answer = "b";
    break;
  default:
    answer = "c";
}

Change the chained if/else if statements into a switch statement. */
function chainToSwitch(val) {
    var answer = "";
    // Only change code below this line
   /* 
    if (val === "bob") {
      answer = "Marley";
    } else if (val === 42) {
      answer = "The Answer";
    } else if (val === 1) {
      answer = "There is no #1";
    } else if (val === 99) {
      answer = "Missed me by this much!";
    } else if (val === 7) {
      answer = "Ate Nine";
    }
    */
    switch (val) {
      case "bob":
      answer = "Marley";
      break;
      case 42:
      answer = "The Answer";
      break;
      case 1:
      answer = "There is no #1";
      break;
      case 99:
      answer = "Missed me by this much!";
      break;
      case 7:
      answer = "Ate Nine";
    }
    // Only change code above this line  
    return answer;  
  }
  
  // Change this value to test
  chainToSwitch(7);
  

ReturnBooleanValuesFromFunction.js

/**Returning Boolean Values from Functions
You may recall from Comparison with the Equality Operator that all comparison operators return a boolean true or false value.

Sometimes people use an if/else statement to do a comparison, like this:

function isEqual(a,b) {
  if (a === b) {
    return true;
  } else {
    return false;
  }
}
But there's a better way to do this. Since === returns true or false, we can return the result of the comparison:

function isEqual(a,b) {
  return a === b;
}

Fix the function isLess to remove the if/else statements. */
function isLess(a, b) {
    // Fix this code
    
      return a <= b;
    
  }
  
  // Change these values to test
  isLess(10, 15);

ReturnEarlyPatternForFunction.js

/**Return Early Pattern for Functions
When a return statement is reached, the execution of the current function stops and control returns to the calling location.

Example

function myFun() {
  console.log("Hello");
  return "World";
  console.log("byebye")
}
myFun();
The above outputs "Hello" to the console, returns "World", but "byebye" is never output, because the function exits at the return statement.


Modify the function abTest so that if a or b are less than 0 the function will immediately exit with a value of undefined.

Hint
Remember that undefined is a keyword, not a string. */

// Setup
function abTest(a, b) {
  // Only change code below this line
  if(a < 0 || b < 0) {
    return undefined;
  }
  
  
  // Only change code above this line

  return Math.round(Math.pow(Math.sqrt(a) + Math.sqrt(b), 2));
}

// Change values below to test your code
abTest(2,2);

SelectingFromManyOptionsWithSwitchStatements.js

/**Selecting from Many Options with Switch Statements
If you have many options to choose from, use a switch statement. A switch statement tests a value and can have many case statements which define various possible values. Statements are executed from the first matched case value until a break is encountered.

Here is a pseudocode example:

switch(num) {
  case value1:
    statement1;
    break;
  case value2:
    statement2;
    break;
...
  case valueN:
    statementN;
    break;
}
case values are tested with strict equality (===). The break tells JavaScript to stop executing statements. If the break is omitted, the next statement will be executed.


Write a switch statement which tests val and sets answer for the following conditions:
1 - "alpha"
2 - "beta"
3 - "gamma"
4 - "delta" */
function caseInSwitch(val) {
    var answer = "";
    // Only change code below this line
    switch(val) {
      case 1:
      answer = "alpha";
      break;
      case 2:
      answer = "beta";
      break;
      case 3:
      answer = "gamma";
      break;
      case 4:
      answer = "delta";
      break;
    }
    
    
    // Only change code above this line  
    return answer;  
  }
  
  // Change this value to test
  caseInSwitch(1);

ShoppingList.js

/**
 * Shopping List
Create a shopping list in the variable myList. The list should be a multi-dimensional array containing several sub-arrays.

The first element in each sub-array should contain a string with the name of the item. The second element should be a number representing the quantity i.e.

["Chocolate Bar", 15]

There should be at least 5 sub-arrays in the list.
 */
var myList = [
    ["Bread", 10],
    ["Milk", 21],
    ["Chocolate", 18],
    ["Banana", 29],
    ["Biscuit", 18]
];

StandInLine.js

/**Stand in Line
In Computer Science a queue is an abstract Data Structure where items are kept in order. New items can be added at the back of the queue and old items are taken off from the front of the queue.

Write a function nextInLine which takes an array (arr) and a number (item) as arguments.

Add the number to the end of the array, then remove the first element of the array.

The nextInLine function should then return the element that was removed. */
function nextInLine(arr, item) {
    // Your code here
  arr.push(item);
  var removed = arr.shift();
    return removed;  // Change this line
  }
  
  // Test Setup
  var testArr = [1,2,3,4,5];
  
  // Display Code
  console.log("Before: " + JSON.stringify(testArr));
  console.log(nextInLine(testArr, 6)); // Modify this line to test
  console.log("After: " + JSON.stringify(testArr));

StoreMultipleValuesInOneVariableUsingJavaScriptArrays.js

/**Store Multiple Values in one Variable using JavaScript Arrays
With JavaScript array variables, we can store several pieces of data in one place.

You start an array declaration with an opening square bracket, end it with a closing square bracket, and put a comma between each entry, like this:

var sandwich = ["peanut butter", "jelly", "bread"].


Modify the new array myArray so that it contains both a string and a number (in that order).

Hint
Refer to the example code in the text editor if you get stuck. */
// Example
var ourArray = ["John", 23];

// Only change code below this line.
var myArray = ["Anna", 35];

StoringValuesWithTheAssignmentOperator.js

/**Storing Values with the Assignment Operator
In JavaScript, you can store a value in a variable with the assignment operator.

myVariable = 5;

This assigns the Number value 5 to myVariable.

Assignment always goes from right to left. Everything to the right of the = operator is resolved before the value is assigned to the variable to the left of the operator.

myVar = 5;
myNum = myVar;
This assigns 5 to myVar and then resolves myVar to 5 again and assigns it to myNum.


Assign the value 7 to variable a.

Assign the contents of a to variable b. */
// Setup
var a;
var b = 2;
a = 7;
b = a;
// Only change code below this line

SubtractOneNumberFromAnotherWithJavaScript.js

/**Subtract One Number from Another with JavaScript
We can also subtract one number from another.

JavaScript uses the - symbol for subtraction.

Example

myVar = 12 - 6; // assigned 6

Change the 0 so the difference is 12. */
var difference = 45 - 33;

TestingObjectsForProperties.js

/**Testing Objects for Properties
Sometimes it is useful to check if the property of a given object exists or not. We can use the .hasOwnProperty(propname) method of objects to determine if that object has the given property name. .hasOwnProperty() returns true or false if the property is found or not.

Example

var myObj = {
  top: "hat",
  bottom: "pants"
};
myObj.hasOwnProperty("top"); // true
myObj.hasOwnProperty("middle"); // false

Modify the function checkObj to test myObj for checkProp. If the property is found, return that property's value. If not, return "Not Found". */
// Setup
var myObj = {
    gift: "pony",
    pet: "kitten",
    bed: "sleigh"
  };
  
  function checkObj(checkProp) {
    // Your Code Here
    if(myObj.hasOwnProperty(checkProp) == true){
      return myObj[checkProp];
    } else {
      return "Not Found";
    }
    
  }
  
  // Test your code by modifying these values
  checkObj("gift");

UnderstandingBooleanValues.js

/**Understanding Boolean Values
Another data type is the Boolean. Booleans may only be one of two values: true or false. They are basically little on-off switches, where true is "on" and false is "off." These two states are mutually exclusive.

Note
Boolean values are never written with quotes. The strings "true" and "false" are not Boolean and have no special meaning in JavaScript.


Modify the welcomeToBooleans function so that it returns true instead of false when the run button is clicked. */
function welcomeToBooleans() {

    // Only change code below this line.
    
    return true; // Change this line
    
    // Only change code above this line.
    }

UnderstandingCaseSensitivityInVariables.js

/**Understanding Case Sensitivity in Variables
In JavaScript all variables and function names are case sensitive. This means that capitalization matters.

MYVAR is not the same as MyVar nor myvar. It is possible to have multiple distinct variables with the same name but different casing. It is strongly recommended that for the sake of clarity, you do not use this language feature.

Best Practice
Write variable names in JavaScript in camelCase. In camelCase, multi-word variable names have the first word in lowercase and the first letter of each subsequent word is capitalized.

Examples:

var someVariable;
var anotherVariableName;
var thisVariableNameIsSoLong;

Modify the existing declarations and assignments so their names use camelCase.
Do not create any new variables. */
// Declarations
var studlyCapVar;
var properCamelCase;
var titleCaseOver;

// Assignments
studlyCapVar = 10;
properCamelCase = "A String";
titleCaseOver = 9000;

UnderstandingUndefinedValueReturnedFromFunction.js

/**Understanding Undefined Value returned from a Function
A function can include the return statement but it does not have to. In the case that the function doesn't have a return statement, when you call it, the function processes the inner code but the returned value is undefined.

Example

var sum = 0;
function addSum(num) {
  sum = sum + num;
}
var returnedValue = addSum(3); // sum will be modified but returned value is undefined
addSum is a function without a return statement. The function will change the global sum variable but the returned value of the function is undefined


Create a function addFive without any arguments. This function adds 5 to the sum variable, but its returned value is undefined. */
// Example
var sum = 0;
function addThree() {
  sum = sum + 3;
}

// Only change code below this line
function addFive() {
  sum = sum + 5;
}


// Only change code above this line
var returnedValue = addFive();

UnderstandingUninitializedVariables.js

/**Understanding Uninitialized Variables
When JavaScript variables are declared, they have an initial value of undefined. If you do a mathematical operation on an undefined variable your result will be NaN which means "Not a Number". If you concatenate a string with an undefined variable, you will get a literal string of "undefined".


Initialize the three variables a, b, and c with 5, 10, and "I am a" respectively so that they will not be undefined. */
// Initialize these three variables
var a;
var b;
var c;

// Do not change code below this line
a = 5;
b = 10;
c = "I am a";
a = a + 1;
b = b + 5;
c = c + " String!";

UnderstandStringImmutability.js

/**Understand String Immutability
In JavaScript, String values are immutable, which means that they cannot be altered once created.

For example, the following code:

var myStr = "Bob";
myStr[0] = "J";
cannot change the value of myStr to "Job", because the contents of myStr cannot be altered. Note that this does not mean that myStr cannot be changed, just that the individual characters of a string literal cannot be changed. The only way to change myStr would be to assign it with a new string, like this:

var myStr = "Bob";
myStr = "Job";

Correct the assignment to myStr so it contains the string value of Hello World using the approach shown in the example above. */
// Setup
var myStr = "Jello World";

// Only change code below this line

myStr = "Hello World"; // Fix Me

UpdatingObjectProperties.js

/**Updating Object Properties
After you've created a JavaScript object, you can update its properties at any time just like you would update any other variable. You can use either dot or bracket notation to update.

For example, let's look at ourDog:

var ourDog = {
  "name": "Camper",
  "legs": 4,
  "tails": 1,
  "friends": ["everything!"]
};
Since he's a particularly happy dog, let's change his name to "Happy Camper". Here's how we update his object's name property:

ourDog.name = "Happy Camper"; or

ourDog["name"] = "Happy Camper";

Now when we evaluate ourDog.name, instead of getting "Camper", we'll get his new name, "Happy Camper".


Update the myDog object's name property. Let's change her name from "Coder" to "Happy Coder". You can use either dot or bracket notation. */
// Example
var ourDog = {
    "name": "Camper",
    "legs": 4,
    "tails": 1,
    "friends": ["everything!"]
  };
  
  ourDog.name = "Happy Camper";
  
  // Setup
  var myDog = {
    "name": "Coder",
    "legs": 4,
    "tails": 1,
    "friends": ["freeCodeCamp Campers"]
  };
  
  // Only change code below this line.
  
  myDog["name"] = "Happy Coder";

UseBracketNotationToFindTheFirstCharacterInAString.js

/**Use Bracket Notation to Find the First Character in a String
Bracket notation is a way to get a character at a specific index within a string.

Most modern programming languages, like JavaScript, don't start counting at 1 like humans do. They start at 0. This is referred to as Zero-based indexing.

For example, the character at index 0 in the word "Charles" is "C". So if var firstName = "Charles", you can get the value of the first letter of the string by using firstName[0].


Use bracket notation to find the first character in the lastName variable and assign it to firstLetterOfLastName.

Hint
Try looking at the firstLetterOfFirstName variable declaration if you get stuck. */
// Example
var firstLetterOfFirstName = "";
var firstName = "Ada";

firstLetterOfFirstName = firstName[0];

// Setup
var firstLetterOfLastName = "";
var lastName = "Lovelace";

// Only change code below this line
firstLetterOfLastName = lastName[0];

UseBracketNotationToFindTheLastCharacterInAString.js

/**Use Bracket Notation to Find the Last Character in a String
In order to get the last letter of a string, you can subtract one from the string's length.

For example, if var firstName = "Charles", you can get the value of the last letter of the string by using firstName[firstName.length - 1].


Use bracket notation to find the last character in the lastName variable.

Hint
Try looking at the lastLetterOfFirstName variable declaration if you get stuck. */
// Example
var firstName = "Ada";
var lastLetterOfFirstName = firstName[firstName.length - 1];

// Setup
var lastName = "Lovelace";

// Only change code below this line.
var lastLetterOfLastName = lastName[lastName.length - 1];

UseBracketNotationToFindTheNth_to_lastCharacterInAString.js

/**Use Bracket Notation to Find the Nth-to-Last Character in a String
You can use the same principle we just used to retrieve the last character in a string to retrieve the Nth-to-last character.

For example, you can get the value of the third-to-last letter of the var firstName = "Charles" string by using firstName[firstName.length - 3]


Use bracket notation to find the second-to-last character in the lastName string.

Hint
Try looking at the thirdToLastLetterOfFirstName variable declaration if you get stuck. */
// Example
var firstName = "Ada";
var thirdToLastLetterOfFirstName = firstName[firstName.length - 3];

// Setup
var lastName = "Lovelace";

// Only change code below this line
var secondToLastLetterOfLastName = lastName[lastName.length - 2];

UseBracketNotationToFindTheNthCharacterInAString.js

/**Use Bracket Notation to Find the Nth Character in a String
You can also use bracket notation to get the character at other positions within a string.

Remember that computers start counting at 0, so the first character is actually the zeroth character.


Let's try to set thirdLetterOfLastName to equal the third letter of the lastName variable using bracket notation.

Hint
Try looking at the secondLetterOfFirstName variable declaration if you get stuck. */
// Example
var firstName = "Ada";
var secondLetterOfFirstName = firstName[1];

// Setup
var lastName = "Lovelace";

// Only change code below this line.
var thirdLetterOfLastName = lastName[2];

UseConditionalLogicWithIfStatement.js

/**Use Conditional Logic with If Statements
If statements are used to make decisions in code. The keyword if tells JavaScript to execute the code in the curly braces under certain conditions, defined in the parentheses. These conditions are known as Boolean conditions and they may only be true or false.

When the condition evaluates to true, the program executes the statement inside the curly braces. When the Boolean condition evaluates to false, the statement inside the curly braces will not execute.

Pseudocode

if (condition is true) {
  statement is executed
}
Example

function test (myCondition) {
  if (myCondition) {
     return "It was true";
  }
  return "It was false";
}
test(true); // returns "It was true"
test(false); // returns "It was false"
When test is called with a value of true, the if statement evaluates myCondition to see if it is true or not. Since it is true, the function returns "It was true". When we call test with a value of false, myCondition is not true and the statement in the curly braces is not executed and the function returns "It was false".


Create an if statement inside the function to return "Yes, that was true" if the parameter wasThatTrue is true and return "No, that was false" otherwise. */
// Example
function ourTrueOrFalse(isItTrue) {
    if (isItTrue) { 
      return "Yes, it's true";
    }
    return "No, it's false";
  }
  
  // Setup
  function trueOrFalse(wasThatTrue) {
  
    // Only change code below this line.
    
    if (wasThatTrue) {
      return "Yes, that was true";
    }
  
    return "No, that was false"; 
    
    // Only change code above this line.
  
  }
  
  // Change this value to test
  trueOrFalse(true);

useMultiplyConditionalOperators.js

/**Use Multiple Conditional (Ternary) Operators
In the previous challenge, you used a single conditional operator. You can also chain them together to check for multiple conditions.

The following function uses if, else if, and else statements to check multiple conditions:

function findGreaterOrEqual(a, b) {
  if(a === b) {
    return "a and b are equal";
  }
  else if(a > b) {
    return "a is greater";
  }
  else {
    return "b is greater";
  }
}
The above function can be re-written using multiple conditional operators:

function findGreaterOrEqual(a, b) {
  return (a === b) ? "a and b are equal" : (a > b) ? "a is greater" : "b is greater";
}

Use multiple conditional operators in the checkSign function to check if a number is positive, negative or zero. */
function checkSign(num) {
    return (num > 0) ? "positive" : (num < 0) ? "negative" : "zero";
  }
  
  checkSign(10);

useTheParseIntFunction.js

/**Use the parseInt Function
The parseInt() function parses a string and returns an integer. Here's an example:

var a = parseInt("007");

The above function converts the string "007" to an integer 7. If the first character in the string can't be converted into a number, then it returns NaN.


Use parseInt() in the convertToInteger function so it converts the input string str into an integer, and returns it. */
function convertToInteger(str) {
    var int = parseInt(str);
    return int;
  }
  
  convertToInteger("56");

useTheParseIntFunctionWithTheRadix.js

/**Use the parseInt Function with a Radix
The parseInt() function parses a string and returns an integer. It takes a second argument for the radix, which specifies the base of the number in the string. The radix can be an integer between 2 and 36.

The function call looks like:

parseInt(string, radix);

And here's an example:

var a = parseInt("11", 2);

The radix variable says that "11" is in the binary system, or base 2. This example converts the string "11" to an integer 3.


Use parseInt() in the convertToInteger function so it converts a binary number to an integer and returns it. */

function convertToInteger(str) {
    var num = parseInt(str, 2);
    return num;
  }
  
  convertToInteger("10011");

useTheTernaryOperator.js

/**Use the Conditional (Ternary) Operator
The conditional operator, also called the ternary operator, can be used as a one line if-else expression.

The syntax is:

condition ? statement-if-true : statement-if-false;

The following function uses an if-else statement to check a condition:

function findGreater(a, b) {
  if(a > b) {
    return "a is greater";
  }
  else {
    return "b is greater";
  }
}
This can be re-written using the conditional operator:

function findGreater(a, b) {
  return a > b ? "a is greater" : "b is greater";
}

Use the conditional operator in the checkEqual function to check if two numbers are equal or not. The function should return either true or false. */

function checkEqual(a, b) {
  

    return a == b ? true : false ;
  }
  
  checkEqual(1, 2);

UsingObjectsForLookups.js

/**Using Objects for Lookups
Objects can be thought of as a key/value storage, like a dictionary. If you have tabular data, you can use an object to "lookup" values rather than a switch statement or an if/else chain. This is most useful when you know that your input data is limited to a certain range.

Here is an example of a simple reverse alphabet lookup:

var alpha = {
  1:"Z",
  2:"Y",
  3:"X",
  4:"W",
  ...
  24:"C",
  25:"B",
  26:"A"
};
alpha[2]; // "Y"
alpha[24]; // "C"

var value = 2;
alpha[value]; // "Y"

Convert the switch statement into an object called lookup. Use it to look up val and assign the associated string to the result variable. */
// Setup
function phoneticLookup(val) {
    var result = "";
  
    // Only change code below this line
    
   
   var lookup = {
    "alpha" : "Adams",
    "bravo" : "Boston",
    "charlie" : "Chicago",
    "delta" : "Denver",
    "echo" : "Easy",
    "foxtrot" : "Frank"
   };
   result = lookup[val];
    // Only change code above this line
    return result;
  }
  
  // Change this value to test
  phoneticLookup("charlie");

WordBlanks.js

/**Word Blanks
We will now use our knowledge of strings to build a "Mad Libs" style word game we're calling "Word Blanks". You will create an (optionally humorous) "Fill in the Blanks" style sentence.

In a "Mad Libs" game, you are provided sentences with some missing words, like nouns, verbs, adjectives and adverbs. You then fill in the missing pieces with words of your choice in a way that the completed sentence makes sense.

Consider this sentence - "It was really ____, and we ____ ourselves ____". This sentence has three missing pieces- an adjective, a verb and an adverb, and we can add words of our choice to complete it. We can then assign the completed sentence to a variable as follows:

var sentence = "It was really" + "hot" + ", and we" + "laughed" + "ourselves" + "silly.";

In this challenge, we provide you with a noun, a verb, an adjective and an adverb. You need to form a complete sentence using words of your choice, along with the words we provide.

You will need to use the string concatenation operator + to build a new string, using the provided variables: myNoun, myAdjective, myVerb, and myAdverb. You will then assign the formed string to the result variable.

You will also need to account for spaces in your string, so that the final sentence has spaces between all the words. The result should be a complete sentence. */
function wordBlanks(myNoun, myAdjective, myVerb, myAdverb) {
    // Your code below this line
    var result = myAdjective + " " + myNoun + " " + myVerb + " " + myAdverb;
  
    // Your code above this line
    return result;
  }
  
  // Change the words here to test your function
  wordBlanks("dog", "big", "ran", "quickly");

WriteReusableJavaScriptWithFunctions.js

/**Write Reusable JavaScript with Functions
In JavaScript, we can divide up our code into reusable parts called functions.

Here's an example of a function:

function functionName() {
  console.log("Hello World");
}
You can call or invoke this function by using its name followed by parentheses, like this:

functionName();

Each time the function is called it will print out the message "Hello World" on the dev console. All of the code between the curly braces will be executed every time the function is called.


Create a function called reusableFunction which prints "Hi World" to the dev console.
Call the function. */
// Example
function ourReusableFunction() {
    console.log("Heyya, World");
  }
  
  ourReusableFunction();
  
  // Only change code below this line
  function reusableFunction() {
      console.log("Hi World");
  }
  reusableFunction();