Operators

Comparison

// I. Comparison Operators:

if ( a == b )  {...  // ==  Equality 
if ( a != b )  {...  // !=  Not Equal to
if ( a === b ) {...  // === Strictly Equal to
if ( a !== b ) {...  // !== Not Strictly Equal to
if ( a > b )   {...  // >   Greater Than
if ( a < b )   {...  // <   Less Than
if ( a >= b )  {...  // >=  Greater Than, or Equal to
if ( a <= b )  {...  // <=  Less Than, or Equal to 



// II. What if we have a more complex comparison?

// 1. LOGICAL AND:
// What if I want to know if a is stricly equal to b AND c is stricly equal to d?
if (a === b AND c === d) {...
// Then we use the double ampersand &&
// The Double Ampersand is known as the 'LOGICAL AND'
// 'The Logical AND' &&
if (a === b && c === d) {...


// 2. Logical OR:
// What if I want to know if a is strictly equal to b OR c is stricly equal to d?
if (a === b OR c === d) {...
// Then we use the double "Pipes" || 
// The Double Pipes is known as the 'LOGICAL OR'
// 'The Logical OR' ||
if (a === b || c === d) {...

// You can even separate these conditionals on multiple lines taking advantage of js ignoring whitespace ( like so... ):

if (
  (a > b)
    && 
  (c < d )  ) {...
  
// III. MODULUS: or, Remainder Operator
// The MODULUS Operator gives us the remainder of the two operands...

// Using MODULUS to calculate a leap year:
var year = 2003;

var remainder = year % 4; // <-- = 3. B/c 4 Goes into year 500 times and the remainder would be 3. 


//  IV. Increment / Decrement: (Unary Operator - Only needs one operand to operate on...)

a = a + 1;

a += 1; 

a++; 

// or..

a = a - 1; 

a -= 1; 

a--; 


// However there is a tricky difference... PREFIX and POSTFIX


// V. PREFIX / POSTFIX:

var a = 5; 
alert(++a); // <-- alert will show a = 6, var a changes BEFORE the alert!

var a = 5; 
alert(a++); // <-- alert will show a = 5, var a changes AFTER the alert!

// The end result is the same but the message alert(); was different!

// VI. TERNARY OPERATOR

//  Unary Operators: (Takes a single operand)
++a

//  Binary Operators: (Takes two operands)
a + b

// Ternary Operators: (Takes three operands!)
condition ? true : false
// you can think of it as a mini if-else statement.

// FOR EXAMPLE: 

// if we we to create two player variables and set their values to a given numeric score each, and, without using a 
// ...ternary operator or condition would look something like thus:

var playerOne = 500;
var playerTwo = 600; 

// sometime later...
var highScore; 

if (playerOne > playerTwo) 
  {
  highScore = playerOne; 
  } 
else  
  {
  highScore = playerTwo; 
  }
}

//  HOWEVER, using a Ternary operator we can consolidate the 
//  ...above six lines of code into about 2 or 3 lines, thusly:

//  Remember the ternary operator takes a condition and then creates a
//  ...conditional logic-switch-gate that is dependent on the conditional 
//  ...being either true or false and then acting on the resulting logical outcome.

// Thus, using a Ternary Operator instead for our above example:

var playerOne = 500;
var playerTwo = 600;

//aleternatively...

//var highScore = // The Ternary Operator

var highScore = (playerOne > playerTwo) ? playerOne : playerTwo; 

//  another way of saying line 128 is:
//  set the variable highScore equal to either playerOne or playerTwo...
//  depending on whether playerOne's score is greater than playerTwo's score.
//  if playerOne IS greater than playerTwo, than highScore = playerOne.
//  if playerOne IS NOT GREATER THAN playerTwo, set highScore = playerTwo. 

// in the above case:

highScore; // <-- 600 | Since playerOne !> playerTwo 
//  (500 !> 600) so highScore = playerTwo.

Equals Operator Diffs

// Equality Operators

//   =  <-- Assignment

//  ==  <-- Equality

// ===  <-- Strict Equality


// == 

var a = 5;
var b = '5';

if ( a === b ) {
  alert("Yes, they're equal!")
}else{
  alert("No, they're NOT equal")
};

// ===

var a = 5;
var b = '5';

if ( a === b ) {
  alert("Yes, they're equal!")
}else{
  alert("No, they're NOT equal")
};

Operators

    // Arithmatic Operators
    
    score = score + 10;
    
    // Short hand...
    
    score += 10; 
    
    // Operator Precedence (Multiplication and Division is MORE IMPORTANT than Addition and Subtraction)
    
    result = 5 + 5 * 10; 
    
    // if unsure wrap in parens 
    
    result = 5 + (5 * 10);
    
    // both will give the same result. . . 
    
    // Assignment instead of Equality:
    
    var a = 5; 
    var b = 10; 
    
    if (a = b) {
      
      // always true!
    
    }
  
  // Why? Keep in mind, one equals sign is an ASSIGNMENT operator it is a command
  // Thus a = b is the command set the value of a equal to b thus b now equals 5 too!
  
  if ( a == b ) {
    alert("Yes, they're equal");
    // Here we use the double equals which is the equality operator, we are ASKING if they are equal. 
    }else{
    alert("No, they're not equal"):
    }
//  EXAMPLE ( '==' THE DOUBLE EQUALS - THE EQUAL OPERATOR )
  var a = 5;
  var b = '5';
  
  if ( a == b ) {
    alert("Yes, they're equal");
  }else{
    alert("No, they're not equal"):
  }
  
  // <- "Yes, they're equal"
  
  // Three equals sign is STRICT EQUALITY. Asking if the operands are NOT JUST EQUAL BUT THE SAME /or IDENTICAL
  
  // EXAMPLE of '===' IDENTICAL OPERATOR
  var a = 5;
  var b = '5';
  
  if ( a === b ) {
    alert("Yes, they're identically equal")
  }else{
    alert("No, they're not identically equal")
  }
  //<--  No, they're not indentically equal"