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Check if object exists in JavaScript

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.


  • 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.


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