Identically Equal and Not Identically Equal

The identically equal operator is ===. The not identically equal operator is !==.

The identically equal and not identically equal operators do not convert operands before testing for equality.

 
<!DOCTYPE html>
<html>
<head>
    <title>Example</title>
    <script type="text/javascript">
    
        var result1 = ("2" == 2); 
        document.writeln(result1);//true - equal because of conversion 
        var result2 = ("2" === 2); 
        document.writeln(result2);//false - not equal because different data types 

       
    </script>
</head>
<body>
</body>
</html>

Click to view the demo

The following code uses the identically equal in an if statement

 
<!DOCTYPE HTML>
<html>
<head>
<title>Example</title>
</head>
<body>
  <script type="text/javascript">
    var firstVal = 5;
    var secondVal = "5";
    if (firstVal === secondVal) {
      document.writeln("They are the same");
    } else {
      document.writeln("They are NOT the same");
    }
  </script>
</body>
</html>

Click to view the demo

The following code shows how to use the not identically equal operator.

 
<!DOCTYPE html>
<html>
<head>
    <title>Example</title>
    <script type="text/javascript">
    
        var result1 = ("5" != 5); 
        document.writeln(result1);//false - equal because of conversion 
        var result2 = ("5" !== 5); 
        document.writeln(result2);//true - not equal because different data types 

       
    </script>
</head>
<body>
</body>
</html>

Click to view the demo

null and undefined are similar values:

 
<!DOCTYPE html>
<html>
<head>
    <title>Example</title>
    <script type="text/javascript">

        var result = (null == undefined); 
        document.writeln(result);//true
       
    </script>
</head>
<body>
</body>
</html>

Click to view the demo

null and undefined are not the same type.

 
<!DOCTYPE html>
<html>
<head>
    <title>Example</title>
    <script type="text/javascript">
    
        var result = (null === undefined); 
        document.writeln(result);//false

       
    </script>
</head>
<body>
</body>
</html>

Click to view the demo

Performing Equality and Identity Tests on Objects

 
<!DOCTYPE HTML>
<html>
<head>
<title>Example</title>
</head>
<body>
  <script type="text/javascript">
    var myData1 = {
      name : "JavaScript",
      weather : "Good",
    };
    var myData2 = {
      name : "JavaScript",
      weather : "Good",
    };
    
    var myData3 = myData2;

    var test1 = myData1 == myData2;
    var test2 = myData2 == myData3;
    var test3 = myData1 === myData2;
    var test4 = myData2 === myData3;
    document.writeln("Test 1: " + test1 + " Test 2: " + test2);
    document.writeln("Test 3: " + test3 + " Test 4: " + test4);
  </script>
</body>
</html>

Click to view the demo

Performing Equality and Identity Tests on Primitives

 
<!DOCTYPE HTML>
<html>
<head>
<title>Example</title>
</head>
<body>
  <script type="text/javascript">
    var myData1 = 5;
    var myData2 = "5";
    var myData3 = myData2;
    var test1 = myData1 == myData2;
    var test2 = myData2 == myData3;
    var test3 = myData1 === myData2;
    var test4 = myData2 === myData3;
    document.writeln("Test 1: " + test1 + " Test 2: " + test2);
    document.writeln("Test 3: " + test3 + " Test 4: " + test4);
  </script>
</body>
</html>

Click to view the demo