jQuery animate passes fixed firstNum, diff to easing function

[tomalec]

jQuery.animete uses easing function with firstNum, diff always set to 0,1:

this.pos = jQuery.easing[specialEasing || defaultEasing](this.state, n, 0, 1, this.options.duration);
this.now = this.start + ((this.end - this.start) * this.pos);

So these parameters are completely useless for easing functions; for example:

swing: function( p, n, firstNum, diff ) {
			return ((-Math.cos(p*Math.PI)/2) + 0.5) * diff + firstNum;
		}
}}

Could be changed to:

swing: function( p, n ) {
			return ((-Math.cos(p*Math.PI)/2) + 0.5);
		}
}}

I suggest changing it to:

this.pos = jQuery.easing[specialEasing || defaultEasing](this.state, n, this.start, this.end - this.start , this.options.duration);
this.now = this.pos;