缓动框架的封装

单个属性：

<button id="btn1">宽变400</button>
<button id="btn2">运动到400</button>
<div id="box"></div>
<script>
    var box=document.getElementById("box");
    var btn1=document.getElementById("btn1");
    var btn2=document.getElementById("btn2");
    btn1.onclick=function(){
        animate(box,"width",400);
    }
    btn2.onclick=function(){
        animate(box,"left",400);
    }
    function animate(ele,attr,target){
        clearInterval(ele.timer);
        ele.timer=setInterval(function(){
            var leader=parseInt(getStyle(ele,attr)) || 0;
            var step=(target-leader)/10;
            step=step>0?Math.ceil(step):Math.floor(step);
            ele.style[attr]=leader+step+"px";
            if(Math.abs(target-leader)<=Math.abs(step)){
                ele.style[attr] = target + "px";
                clearInterval(ele.timer);
            }
        },30)
    }
    function getStyle(ele,attr){
        if(ele.currentStyle){
            return ele.currentStyle[attr];
        }else{
            return getComputedStyle(ele,false)[attr];
        }
    }
</script>

<style>
    *{
        margin: 0;
        padding: 0;
    }
    #box{
        100px;
        height:100px;
        background: pink;
        position: absolute;
    }
</style>

多个属性：

<style>
    div {
        position: absolute;
        top: 40px;
        left: 10px;
         100px;
        opacity: 0.6;
        height: 100px;
        background-color: pink;
    }
</style>

<button>运动到400然后回来</button>
    <div></div>
    <script>
        var btnArr = document.getElementsByTagName("button");
        var div = document.getElementsByTagName("div")[0];

        btnArr[0].onclick = function () {
            var json1 = {"left":300,"top":200,"width":300,"height":200,"opacity": 30,"zIndex": 1};
            animate(div,json1);
        }
        function animate(ele,json,fn){
            clearInterval(ele.timer);
            ele.timer = setInterval(function () {
                var bool = true;
                for(var k in json){
                    var leader;
                    if(k === "opacity"){
                        leader = getStyle(ele,k)*100 || 1;
                    }else{
                        leader = parseInt(getStyle(ele,k)) || 0;
                    }
                    var step = (json[k] - leader)/10;
                    step = step>0?Math.ceil(step):Math.floor(step);
                    leader = leader + step;
                    if(k === "opacity"){
                        ele.style[k] = leader/100;
                        ele.style.filter = "alpha(opacity="+leader+")";
                    }else if(k === "zIndex"){
                        ele.style.zIndex = json[k];
                    }else{
                        ele.style[k] = leader + "px";
                    }
                    if(json[k] !== leader){
                        bool = false;
                    }
                }
                if(bool){
                    clearInterval(ele.timer);
                    if(fn){
                        fn();
                    }
                }
            },25);
        }
        function getStyle(ele,attr){
            if(window.getComputedStyle){
                return window.getComputedStyle(ele,null)[attr];
            }
            return ele.currentStyle[attr];
        }
    </script>