JavaScript undefined replaced with null

Question

In JavaScript undefined can be reassigned, so it is often advised to create a self executing function that assures undefined is actually undefined. As an alternati

Answer 1

Because of this:

var myVar1;
var myVar2 = null;

if (myVar1 === null) alert('myVar1 is null');
if (myVar1 === undefined) alert('myVar1 is undefined');
if (myVar2 === null) alert('myVar2 is null');
if (myVar2 === undefined) alert('myVar2 is undefined');

Anything set to null is not undefined - it's defined as null.