# What is typeof Operator in JavaScript?

JavascriptWeb DevelopmentFront End Technology

The typeof operator is a unary operator that is placed before its single operand, which can be of any type. Its value is a string indicating the data type of the operand.  The typeof operator evaluates to "number", "string" or "boolean" if its operand is a number, string, or boolean value and returns true or false based on the evaluation.

Here is a list of the return values for the typeof Operator.

Type
String Returned by typeof
Number
"number"
String
"string"
Boolean
"boolean"
object
"object"
Function
"function"
Undefined
"undefined"
Null
"object"

## Example

The following code shows how to implement typeof operator −

<html>
<body>
<script>
var a = 10;
var b = "String";
var linebreak = "<br />";

result = (typeof b == "string" ? "B is String" : "Bis Numeric");
document.write("Result => ");
document.write(result);
document.write(linebreak);

result = (typeof a == "string" ? "A is String" : "Ais Numeric");
document.write("Result => ");
document.write(result);
document.write(linebreak);
</script>
</body>
</html>
Published on 19-Jan-2018 05:35:54