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>