妙味——任意值变化的运动框架

function getStyle(obj,attr){
    if(obj.currentStyle)
    {
        return obj.currentStyle[attr];
    }
    else
    {
        return getComputedStyle(obj,false)[attr];
    }
}
// var timer=null;
function startMove(obj,attr,iTarget){

    clearInterval(obj.timer);
    obj.timer=setInterval(function(){
        // var iCur=parseInt(getStyle(obj,attr));
        var iCur=0;

        if(attr=='opacity')
        {
            iCur=parseInt(parseFloat(getStyle(obj,attr))*100);
        }
        else
        {
            iCur=parseInt(getStyle(obj,attr));
        }

        var iSpeed=(iTarget-iCur)/8;
        iSpeed=iSpeed>0?Math.ceil(iSpeed):Math.floor(iSpeed);

        if(iCur==iTarget){
            clearInterval(obj.timer);
        }
        else{
            if(attr=='opacity')
            {
                obj.style.opacity=(iCur+iSpeed)/100;
                obj.style.filter='alpha(opacity:'+(iCur+iSpeed)+')';
            }
            else
            {
                obj.style[attr]=iCur+iSpeed+'px';
            }
        }
    },30);
}