额，jQuery的性能和功能很强悍，可悲的是jQuery代码各种关联啊，不方便阅读和分离，所以找了一个简单的引擎，把源码贴出来，有兴趣的可以读一下代码。
这个引擎的代码还是比较简单的，入门级的。
/**
* 功能参数如下：
* ease --> 具体缓动类型
* onComplete --> 动作运行结束时调用
* onUpdate --> 动作正在运行时调用
* delay --> 动作延迟指定秒数后执行
* ------------->
* Z.Key
* Download by http://www.codefans.net
* 2012-05-10
* http://www.oozk.net/learn/
*/
var TweenLite = function($target,$duration,$vars){
var ease,
onComplete,
onUpdate,
delay,
vars = $vars,
target = $target,
speed = $duration;
if(!target) return false;
if(vars.ease){
ease = vars.ease;
delete vars.ease;
}else{
ease = Easing.Linear;
}
if(vars.onComplete){onComplete = vars.onComplete;delete vars.onComplete;}
if(vars.onUpdate){onUpdate = vars.onUpdate;delete vars.onUpdate;}
if(vars.delay){delay = vars.delay;delete vars.delay;}
var ifstop = false;
var attrArr = [];
var curArr = [];
var initArr = [];
for(var at in vars){
attrArr.push(at);
curArr.push(vars[at]);
var atObj = at=='alpha' ? parseInt(parseFloat(getStyle(target,'opacity'))*100) : parseInt(getStyle(target,at));
if(isNaN(atObj))atObj = 100;
initArr.push(atObj);
}
if(delay){
if(target.delay) clearTimeout(target.delay);
target.delay = setTimeout(run,delay*1000);
}else{
run();
}
function run(){
var s = (new Date()).getTime() / 1000;
for(var attr in vars){
(function(){
var t = (new Date()).getTime() / 1000 - s;
for(var i=0;i<attrArr.length;i++){
var easeVars = ease(t,initArr[i],curArr[i]-initArr[i],speed);
if(attrArr[i]=='alpha'){
target.style["opacity"] = easeVars / 100;
target.style["filter"] = "alpha(opacity:"+easeVars+")";
}else{
target.style[attrArr[i]] = attrArr[i]=="zIndex" ? parseInt(easeVars) : parseInt(easeVars) + "px";
}
}
if(target.timer) clearTimeout(target.timer);
if(t<speed){
target.timer = setTimeout(arguments.callee, 10);
if(onUpdate)onUpdate();
}else{
if(!ifstop){
ifstop = true;
clearTimeout(target.timer);
if(onComplete)onComplete();
}
}
})()
}
}
function getStyle(ta, at){
return ta.currentStyle?ta.currentStyle[at]:getComputedStyle(ta, false)[at];
}
}
/**
* 以下是各种缓动公式算法
* t: current time（当前时间）；
* b: beginning value（初始值）；
* c: change in value（变化量）；
* d: duration（持续时间）
*/
var Easing = {
Linear: function(t,b,c,d){ return c*t/d + b; },
Quad: {
easeIn: function(t,b,c,d){
return c*(t/=d)*t + b;
},
easeOut: function(t,b,c,d){
return -c *(t/=d)*(t-2) + b;
},
easeInOut: function(t,b,c,d){
if ((t/=d/2) < 1) return c/2*t*t + b;
return -c/2 * ((--t)*(t-2) - 1) + b;
}
},
Cubic: {
easeIn: function(t,b,c,d){
return c*(t/=d)*t*t + b;
},
easeOut: function(t,b,c,d){
return c*((t=t/d-1)*t*t + 1) + b;
},
easeInOut: function(t,b,c,d){
if ((t/=d/2) < 1) return c/2*t*t*t + b;
return c/2*((t-=2)*t*t + 2) + b;
}
},
Quart: {
easeIn: function(t,b,c,d){
return c*(t/=d)*t*t*t + b;
},
easeOut: function(t,b,c,d){
return -c * ((t=t/d-1)*t*t*t - 1) + b;
},
easeInOut: function(t,b,c,d){
if ((t/=d/2) < 1) return c/2*t*t*t*t + b;
return -c/2 * ((t-=2)*t*t*t - 2) + b;
}
},
Quint: {
easeIn: function(t,b,c,d){
return c*(t/=d)*t*t*t*t + b;
},
easeOut: function(t,b,c,d){
return c*((t=t/d-1)*t*t*t*t + 1) + b;
},
easeInOut: function(t,b,c,d){
if ((t/=d/2) < 1) return c/2*t*t*t*t*t + b;
return c/2*((t-=2)*t*t*t*t + 2) + b;
}
},
Sine: {
easeIn: function(t,b,c,d){
return -c * Math.cos(t/d * (Math.PI/2)) + c + b;
},
easeOut: function(t,b,c,d){
return c * Math.sin(t/d * (Math.PI/2)) + b;
},
easeInOut: function(t,b,c,d){
return -c/2 * (Math.cos(Math.PI*t/d) - 1) + b;
}
},
Expo: {
easeIn: function(t,b,c,d){
return (t==0) ? b : c * Math.pow(2, 10 * (t/d - 1)) + b;
},
easeOut: function(t,b,c,d){
return (t==d) ? b+c : c * (-Math.pow(2, -10 * t/d) + 1) + b;
},
easeInOut: function(t,b,c,d){
if (t==0) return b;
if (t==d) return b+c;
if ((t/=d/2) < 1) return c/2 * Math.pow(2, 10 * (t - 1)) + b;
return c/2 * (-Math.pow(2, -10 * --t) + 2) + b;
}
},
Circ: {
easeIn: function(t,b,c,d){
return -c * (Math.sqrt(1 - (t/=d)*t) - 1) + b;
},
easeOut: function(t,b,c,d){
return c * Math.sqrt(1 - (t=t/d-1)*t) + b;
},
easeInOut: function(t,b,c,d){
if ((t/=d/2) < 1) return -c/2 * (Math.sqrt(1 - t*t) - 1) + b;
return c/2 * (Math.sqrt(1 - (t-=2)*t) + 1) + b;
}
},
Elastic: {
easeIn: function(t,b,c,d,a,p){
if (t==0) return b; if ((t/=d)==1) return b+c; if (!p) p=d*.3;
if (!a || a < Math.abs(c)) { a=c; var s=p/4; }
else var s = p/(2*Math.PI) * Math.asin (c/a);
return -(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
},
easeOut: function(t,b,c,d,a,p){
if (t==0) return b; if ((t/=d)==1) return b+c; if (!p) p=d*.3;
if (!a || a < Math.abs(c)) { a=c; var s=p/4; }
else var s = p/(2*Math.PI) * Math.asin (c/a);
return (a*Math.pow(2,-10*t) * Math.sin( (t*d-s)*(2*Math.PI)/p ) + c + b);
},
easeInOut: function(t,b,c,d,a,p){
if (t==0) return b; if ((t/=d/2)==2) return b+c; if (!p) p=d*(.3*1.5);
if (!a || a < Math.abs(c)) { a=c; var s=p/4; }
else var s = p/(2*Math.PI) * Math.asin (c/a);
if (t < 1) return -.5*(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
return a*Math.pow(2,-10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )*.5 + c + b;
}
},
Back: {
easeIn: function(t,b,c,d,s){
if (s == undefined) s = 1.70158;
return c*(t/=d)*t*((s+1)*t - s) + b;
},
easeOut: function(t,b,c,d,s){
if (s == undefined) s = 1.70158;
return c*((t=t/d-1)*t*((s+1)*t + s) + 1) + b;
},
easeInOut: function(t,b,c,d,s){
if (s == undefined) s = 1.70158;
if ((t/=d/2) < 1) return c/2*(t*t*(((s*=(1.525))+1)*t - s)) + b;
return c/2*((t-=2)*t*(((s*=(1.525))+1)*t + s) + 2) + b;
}
},
Bounce: {
easeIn: function(t,b,c,d){
return c - Easing.Bounce.easeOut(d-t, 0, c, d) + b;
},
easeOut: function(t,b,c,d){
if ((t/=d) < (1/2.75)) {
return c*(7.5625*t*t) + b;
} else if (t < (2/2.75)) {
return c*(7.5625*(t-=(1.5/2.75))*t + .75) + b;
} else if (t < (2.5/2.75)) {
return c*(7.5625*(t-=(2.25/2.75))*t + .9375) + b;
} else {
return c*(7.5625*(t-=(2.625/2.75))*t + .984375) + b;
}
},
easeInOut: function(t,b,c,d){
if (t < d/2) return Easing.Bounce.easeIn(t*2, 0, c, d) * .5 + b;
else return Easing.Bounce.easeOut(t*2-d, 0, c, d) * .5 + c*.5 + b;
}
}
}
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