a developer's notes – a semi-technical web development BLOG

September 5, 2011

Check for null or undefined in Javascript

Filed under: Javascript / JQuery — Duy Nguyen @ 12:34 pm
Tags: , , , ,

Here is how you can check if a variable is null or undefined.

function MyMethod() {
     var myVar = document.getElementById('something');
     if(typeof(myVar) !== 'undefined' && myVar!= null) {
          return myVar.checked;

OR this…

if( value ) {

will evaluate to true if value is not:

empty string (“”)

Leave a Comment »

No comments yet.

RSS feed for comments on this post. TrackBack URI

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Blog at WordPress.com.

%d bloggers like this: