Check if a variable exists in JavaScript

admin — Sat, 02 May 2009 16:43:18 +0000

At times, you might want to check if a variable exists. Here’s how you can do it:

if (typeof VariableName != 'undefined')

where, of course, VariableName is the actual name of your variable.
But what if you know for sure that your variable exists, but you don’t know if it stores a value?
This little Javascript snippet can help:

if (undefined != VariableName)

Creative Impact

Check if a variable exists in JavaScript