Check if a variable exists in JavaScript
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)