JQuery ‘exists’ and ‘checked’ functionality

  • April 20, 2010
  • None

One of the brilliant things about jquery is that it’s so easy to extend, whether that be by writing your own full blown plugin, or with a quick 1 liner to add new functionality.

Here’s a couple that I always find handy. First up, adding an ‘exists’ function, so you can do this:

if ($(selector).exists()){
    //do something here if our selected element exists
}

the code is really quite simple, basically we return true if the JQuery object returned by our selector has a length greater than 0 (ie: if the selector matches anything), and false if it doesn’t.

jQuery.fn.exists = function(){
          return jQuery(this).length>0;
}

Next we have something I use all the time, a really simple function that returns true if the checkbox element you call it on is in the ‘checked’ state, and false if it isn’t. So you can do this:

if ('#mycheckbox').checked(){
      //do something here if the checkbox is checked
}

and the code to add that function is:

jQuery.fn.checked = function(){
         return jQuery(this).is(':checked');
}

Hopefully those will be of use to someone else, they’re not particularly complex but they can make your code easier to understand and save you a bit of typing.




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