typeof () is a variable of type object in JavaScript to add properties

Code 01:int

var a = 10;a.name = "HelloWorld"; alert (a.name);

Output

Undefined

Code 02:string

var a = "abc"; a.name = "HelloWorld"; alert (a.name);

Output

Undefined

Code 03:string

var a = new String (); a.name = "HelloWorld"; alert (a.name);

Or

var a = new String ("abc"); a.name = "HelloWorld"; alert (a.name);

Output

HelloWorld

Code 04:object

var a = {};a.name = "HelloWorld"; alert (a.name);

Or

var a = new Object (); a.name = "HelloWorld"; alert (a.name);

Output

HelloWorld

From these sets of code, some output is undefined, and some output is HelloWorld, which is related to the data type stored in a.

The result of typeof (10) is number

The result of typeof ("ABC") is String

The result of typeof ("ABC") is an object

The result of typeof (New Object ()) is an object

The summary of these pieces of code is that only typeof () gets a variable of type object to add the custom property .

typeof () is a variable of type object in JavaScript to add properties