JavaScript typeof Operator Tutorial

JavaScript typeof operator is used to get the datatype of its operand. Operand can be any function, object or variable.

Syntax :

typeof (operand)

JavaScript typeof Operator String Example

<html>
<head>
<title>Developer Helps | Javascript typeof Operator</title>
</head>
<body>
<h2>Javascript typeof</h2>
<p id="empty-string"></p>
<p id="single-word"></p>
<p id="multiple-word"></p>

<script>
var language1 = "";
var language2 = "PHP";
var language3 = "Java WordPress";

document.getElementById("empty-string").innerHTML = typeof(language1);
document.getElementById("single-word").innerHTML = typeof(language2);
document.getElementById("multiple-word").innerHTML = typeof(language3);
</script>

</body>
</html>

Output :

Javascript typeof

string
string
string

JavaScript Number Datatype Example

<html>
<head>
<title>Developer Helps | Javascript typeof Operator</title>
</head>
<body>
<h2>Javascript typeof</h2>
<p id="number-type"></p>

<script>
document.getElementById("number-type").innerHTML = typeof(9) + "<br>" + typeof(9.45) + "<br>" + typeof(0);
</script>

</body>
</html>

Output :

Javascript typeof
number
number
number

JavaScript Undefined Datatype Example

In JavaScript, a variable without a value, has the value undefined.

<html>
<head>
<title>Developer Helps | Javascript typeof Operator</title>
</head>
<body>
<h2>Javascript typeof</h2>
<p id="undefined-type"></p>

<script>
var lang;
document.getElementById("undefined-type").innerHTML = typeof(lang);
</script>

</body>
</html>

Output :

Javascript typeof

undefined

JavaScript Object Datatype Example

In JavaScript, typeof operator returns the “object” for the objects and arrays or null.

<html>
<head>
<title>Developer Helps | Javascript typeof Operator</title>
</head>
<body>
<h2>Javascript typeof</h2>
<p id="object-type"></p>

<script>
var arr = ["PHP", "Java"];
var obj = {language:"PHP", framework:"Laravel"};
var value = null;

document.getElementById("object-type").innerHTML = "Array is: " + typeof(arr) + "<br>Object is: " + typeof(obj) + "<br>null is: " + typeof(value);
</script>

</body>
</html>

Output :

Javascript typeof

Array is: object
Object is: object
null is: object

JavaScript Boolean Datatype Example

Boolean type value is true or false.

<html>
<head>
<title>Developer Helps | Javascript typeof Operator</title>
</head>
<body>
<h2>Javascript typeof</h2>
<p id="boolean-type"></p>

<script>
var bool = true ;
document.getElementById("boolean-type").innerHTML = typeof(bool);
</script>

</body>
</html>

Output :