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typeof Operator with Example in JavaScript

JavaScript typeof Operator: Here, we are going to learn what is typeof operator in JavaScript and how it is used?
Submitted by IncludeHelp, on February 01, 2019

JavaScript typeof Operator

"typeof" is an operator in JavaScript and it is used to return the data type of a variable, value, expression i.e. operand.

Syntax:

typeof variable/value/expression;
or
typeof (variable/value/expression);

Example:

<html>
<head>
<title>JavaScipt Example</title>
</head>

<body>
	<script>		
		var a = 10;
		var b = 10.23;
		var c = "Hello";
		var d; 
		var e = "10+20";
		
		//printing type of variables
		document.write("type of a: " + typeof a + "<br>");
		document.write("type of b: " + typeof b + "<br>");
		document.write("type of c: " + typeof c + "<br>");
		document.write("type of d: " + typeof d + "<br>");
		document.write("type of e: " + typeof e + "<br>");
		
		//some of the expressions
		document.write(typeof (a+b) + "<br>");
		document.write(typeof (a+b+c) + "<br>");
		document.write(typeof (a+b+c+d) + "<br>");
		document.write(typeof (a+b+c+e) + "<br>");
		document.write(typeof (10+20+1.23) + "<br>");
		document.write(typeof (NaN) + "<br>");
	</script>
</body>
</html>

Output

type of a: number
type of b: number
type of c: string
type of d: undefined
type of e: string
number
string
string
string
number
number




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