'!=' comparison operator
'!=' operator checks the unequality of two objects without making the type check. It converts the datatype of two operands to one and then compares their value. For example 1 != '1' will results false.
'!==' comparison operator
'!==' operator checks the unequality of two objects with a type check. It does not converts the datatype and makes a typed check.For example 1 !== '1' will results true.
Following example, shows usage of '!=' vs '!==' operators.
Example
<!DOCTYPE html>
<html>
<head>
<title>Operator Example</title>
</head>
<body>
<script language="JavaScript">
console.log(" 1 != '1' " + (1 != '1'));
console.log(" 1 !== '1' " + (1 !== '1'));
</script>
</body>
</html>Output
1 != '1' false 1 !== '1' true