js完美运动框架

function doMove(obj,json,fn){                        
    var iCur = 0;
    var alpha = 0;

    clearInterval(obj.timer);
    obj.timer = setInterval(function(){
        var bStop = true;
        for(var attr in json){
            if(attr == 'opacity'){
                iCur = parseInt(parseFloat(getStyle(obj,attr))*100);
            }else{
                iCur = parseInt(getStyle(obj,attr));
            }


            var iSpeed = (json[attr]-iCur)/15;
            iSpeed = iSpeed>0?Math.ceil(iSpeed):Math.floor(iSpeed);

            if(iCur != json[attr]){
                bStop = false;
            }
            if(attr == 'opacity'){
                alpha = iCur + iSpeed;
                obj.style.filter = 'alpha(opacity='+alpha+')';
                obj.style[attr] = alpha/100;
            }else{
                obj.style[attr] = iCur + iSpeed + 'px';
            }
        }
        if(bStop){
            clearInterval(obj.timer);
            fn&&fn();
        }

    },20)

}

function getStyle ( obj, attr ) {                               
    return obj.currentStyle?obj.currentStyle[attr] : getComputedStyle( obj )[attr];
}