How to use undefined Property in JavaScript

This article describe about undefined Property in JavaScript.
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undefined Property in JavaScript

If variable has not assigned value then it is indicated by the undefined property.


<!DOCTYPE html>



<script type="text/javascript">

    var a = "";

    var b;

    if (a == undefined) {

        document.write("a is undefined");


    if (b == undefined) {

        document.write("b is undefined");







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