JS封装运动框架的一种写法

function animate(obj, json, interval, sp, fn) {
 clearInterval(obj.timer);
 //var k = 0;
 //var j = 0;
 function getStyle(obj, arr) {
 if(obj.currentStyle){
 return obj.currentStyle[arr]; //针对ie
 } else {
 return document.defaultView.getComputedStyle(obj, null)[arr]; 
 }
 }
 obj.timer = setInterval(function(){
 //j ++;
 var flag = true;
 for(var arr in json) {
 var icur = 0;
 //k++;
 if(arr == "opacity") {
 icur = Math.round(parseFloat(getStyle(obj, arr))*100);
 } else {
 icur = parseInt(getStyle(obj, arr));
 }
 var speed = (json[arr] - icur) * sp;
 speed = speed > 0 ? Math.ceil(speed): Math.floor(speed);
 if(icur != json[arr]){
 flag = false;
 } 
 if(arr == "opacity"){
 obj.style.filter = "alpha(opacity : '+(icur + speed)+' )";
 obj.style.opacity = (icur + speed)/100;
 }else {
 obj.style[arr] = icur + speed + "px";
 }
 //console.log(j + "," + arr +":"+ flag);
 }
 if(flag){
 clearInterval(obj.timer);
 //console.log(j + ":" + flag); 
 //console.log("k = " + k);
 //console.log("j = " + j);
 //console.log("DONE");
 if(fn){
 fn();
 }
 }
 },interval);
}