Catch checked change event of a checkbox

The click will affect a label if we have one attached to the input checkbox?

I think that is better to use the .change() function

<input type="checkbox" id="something" />

$("#something").change( function(){
  alert("state changed");
});

<input type="checkbox" id="something" />

$("#something").click( function(){
   if( $(this).is(':checked') ) alert("checked");
});

Edit: Doing this will not catch when the checkbox changes for other reasons than a click, like using the keyboard. To avoid this problem, listen to changeinstead of click.

For checking/unchecking programmatically, take a look at Why isn't my checkbox change event triggered?