I am trying to wrap up a plugin that I am writing but am stumped on a very trivial problem that I cant seem to find a solution for. I have tracked down almost every forum and related problem discussion. Any ways here is what I want to happen, my plugin has a timer that I would like the user to be able to handle its termination.

(function ($) {
...
var defaults = {
 callback : function(){},
 crossfadeTime : 1000,
 easing : 'linear',
 running : 'true', // Here is where I would like the user to send a parameter 
                   // to invoke a different result. i.e. 'false' => clearing 
                   // the timer. Such as...

var timer = setInterval(function(){
  // Do Something;
},3000);

if(defaults.running == 'false'){
  clearInterval(timer);
}