Check if object exists in JavaScript

Question

How do I verify the existence of an object in JavaScript?

The following works:

if (!null)    alert("GOT HERE"); 

But this throws an Error:

if (!maybeObject)    alert("GOT HERE"); 

The Error:

maybeObject is not defined.

Answer 1

You can safely use the typeof operator on undefined variables.

If it has been assigned any value, including null, typeof will return something other than undefined. typeof always returns a string.

Therefore

if (typeof maybeObject != "undefined") {    alert("GOT THERE"); }