function getByClass(oParent, sClass) {
    if (oParent.getElementsByClassName) {
        return oParent.getElementsByClassName(sClass);
    } else {  
        var arr = [];
        var reg = new RegExp('\\b' + sClass + '\\b');
        var aEle = oParent.getElementsByTagName('*');
        for (var i = 0; i < aEle.length; i++) {
            if (reg.test(aEle[i].className)) {
                arr.push(aEle[i]);
            }
        }
        return arr;
    }
}

function getStyle(obj,name){
    return (obj.currentStyle || getComputedStyle(obj,false))[name];
};

function move(obj,json,options){
    options=options||{};
    options.time=options.time||500;
    options.type=options.type||"ease-out";
    var dis={};
    var start={};
    for(var name in json){
        if(name=='opacity'){
            start[name]=parseFloat(getStyle(obj,name));
        }else{
            start[name]=parseInt(getStyle(obj,name));
        }
        if(isNaN(start[name])){
            switch(name){
                case "left":
                    start[name]=obj.offsetLeft;
                    break;
                case "top":
                    start[name]=obj.offsetTop;
                    break;
                case "width":
                    start[name]=obj.offsetWidth;
                    break;
                case "height":
                    start[name]=obj.offsetHeight;
                    break;
            }
        }
        dis[name]=json[name]-start[name];
    }
    var n=0;
    var count=Math.round(options.time/30);
    clearInterval(obj.timer);
    obj.timer=setInterval(function(){
        n++;
        for(var name in json){
            switch(options.type){
                case "linaer":
                    var cur=start[name]+dis[name]*n/count;
                    break;
                case "ease-in":
                    var a=n/count;
                    var cur=start[name]+dis[name]*a*a*a;
                    break;
                case "ease-out":
                    var a=1-n/count;
                    var cur=start[name]+dis[name]*(1-a*a*a);
                    break;
            }
            if(name=='opacity'){
                obj.style.opacity=cur;
                obj.style.filter="alpha(opacity:"+cur*100+")";
            }else{
                obj.style[name]=cur+"px";
            }
        }

        if(n==count){
            clearInterval(obj.timer);
            options.fn&&options.fn();
        }
    },30);
};