Treat undefined the same as null, you can use the equality operator (==) in JavaScript
Description
The following code shows how to treat undefined the same as null, you can use the equality operator (==).
Example
<!DOCTYPE HTML>
<html>
<body>
<script type="text/javascript">
var firstVal = null;<!-- w w w. j av a 2 s . c o m-->
var secondVal;
var equality = firstVal == secondVal;
var identity = firstVal === secondVal;
document.writeln("Equality: " + equality);
document.writeln("Identity: " + identity);
</script>
</body>
</html>
The code above generates the following result.
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Create undefined value by defining a variab...
Differentiate between null and undefined, y...
Find out the difference between undefined v...