Week 2 Day 2 Checkpoint for Eliot Mason

w2d2-checkpoint-ej-mason.js

/*
EJ Mason
August 23, 2016
Week 2

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							W2D2 Checkpoint
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*/

/*
1. Write a function average that takes two numbers as input (parameters), and
   returns the average of those numbers.
*/

function average (firstNum, secondNum){ // GOOD JOB!
	return (firstNum + secondNum) / 2;
}



/*
2. Write a function greeter that takes a name as an argument and greets that
   name by returning something along the lines of "Hello, <name>!"
*/

function greeter(name){ // GOOD JOB!, the only thing is you forgot the semicolon on line 28
	return 'Hello ' + name + '!'
}

/*
3. Write the following functions that each accept a single number as
   an argument:
		- even: returns true if its argument is even, and false otherwise.
		- odd: the opposite of the above.
		- positive: returns true if its argument is positive, and false
		  otherwise.
		- negative: the opposite of the above.
*/

function even(number){ // Good Job!
	if(number % 2 === 0){
		return true;
	}
	return false;
}

function odd(number){
	if(number % 2 === 0){
		return false;
	}
	return true;
}

function positive(number){ // Good job!
	if(number === 0){
		return 'Error, 0 is unsigned';
	}
	else{
		if(number > 0){
			return true;
		}
		return false;
	}
}

function negative(number){ // Good Job!
	if(number === 0){
		return 'Error, 0 is unsigned';
	}
	else{
		if(number < 0){
			return true;
		}
		return false;
	}
}

/*
4. Write a function sayHello that takes a language parameter, and returns
   "hello" in that language. Make the function work with at least three
   languages.
*/

function sayHello(language){ // Good Job!
	if(language.toLowerCase() === 'english'){
		return 'Hello';
	}
	if(language.toLowerCase() === 'spanish'){
		return 'Hola';
	}
	if(language.toLowerCase() === 'portuguese'){
		return 'Ola';
	}
}

/*
5. Write a function validCredentials that accepts two parameters: username
   and password, and returns true if both are long enough, and false otherwise.
   You can decide what constitutes "long enough".
*/

function validCredentials(username, password){ // Good Job!
	//password and username must be at least 8 chars
	if(username.length > 7){
		if(password .length > 7){
			return true;
		}
	}
	return false;
}

/*
6. Repeating a String n Times: Let's write a function called repeatString
   that takes two parameters: a string str, which is the string to be repeated,
   and count -- a number representing how many times the string str should be
   repeated.
*/

function repeatString(str, count){ // Good Job!, i like your use of recursion here!
	if(count === 0){
		return '';
	}
	else{
		return str + repeatString(str, count - 1);
	}
}

repeatString('dog', 0); // => ''
repeatString('dog', 1); // => 'dog'
repeatString('dog', 2); // => 'dog' + 'dog' => 'dogdog'
repeatString('dog', 3); // => 'dog' + 'dog' + 'dog' => 'dogdogdog'

/*
7. Write a function called average that takes an array of numbers as a
   parameter and returns the average of those numbers.
*/
function average(inArray){ // Good Job!
	var answer = 0;

	for(var i = 0; i < inArray.length; i++){
		answer += inArray[i];
	}
	return answer / inArray.length;
}

/*
8. Write a function countWords that, when given a string as an argument,
   returns an object where keys are the words in the string, and values
   are the number of occurrences of that word within the string:
*/

//helper function
function keyExists(myObject, stringToCheck){ // Good Job!
	var alreadyExists = false;

	
	for (var key in myObject){
		if(key === stringToCheck){
			alreadyExists = true;
		}
	}

	return alreadyExists;
}

function countWords(s) { // Good Job!
	
	//uncomment below and comment line 170 for case insensitive;
	//var newArray = s.toLowerCase().split(' ');

	var newArray = s.split(' ');

	var newObject = {};
	newObject[newArray[0]] = 1;

	//does not need to enter loop if array only contained one word
	if(newArray.length === 1){
		return newObject;
	}
	//If there is more than one word in array
	else{
		for (var i = 1; i < newArray.length; i++){

			if(keyExists(newObject, newArray[i])){
				newObject[newArray[i]] += 1;
			}
			else{
				newObject[newArray[i]] = 1;
			}
		}
	}
	return newObject;
}

countWords("hello hello"); // => {"hello": 2}
countWords("Hello hello"); // => {"Hello": 1, "hello": 1}
countWords("The quick brown"); // => {"The": 1, "quick": 1, "brown": 1}




/*
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								BONUS
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*/
/*
1. Read about the join method on MDN and use it to implement a function that 
accepts a string as an argument and returns that string reversed.
*/

function stringReversed(inString){ // Good Job!
	var newString = '';

	for(var i = inString.length - 1; i >= 0; i--){
		newString += inString[i];
	}

	return newString;
}


/*
2. The function Object.keys returns an array of an object's keys. 
   Experiment with it at the console like this:

		Object.keys({a: 1, b: 2});  //returns array of keys

   Using this property, write versions of the above functions using 
   repetition through function invocation (i.e. recursion)

*/