code: function( from, to, unit ) {
  		this.startTime = now();
  		this.start = from;
  		this.end = to;
  		this.unit = unit || this.unit || "px";
  		this.now = this.start;
  		this.pos = this.state = 0;
  
  		var self = this;
  		function t( gotoEnd ) {
  			return self.step(gotoEnd);
  		}
  
  		t.elem = this.elem;
  
  		if ( t() && jQuery.timers.push(t) && !timerId ) {
  			timerId = setInterval(jQuery.fx.tick, 13);
  		}
  	}
docs: Start an animation from one number to another