js的运动框架

/**
 * Created by zhouhaiou on 2015/6/10.
 */


// 封装获取id的方法
function $(id){
    return document.getElementById(id);
}

// 封装获取class的方法

function getClass(className,parent){
    var oParent = parent ? $(parent) : document,
        eles = [],
        elements = oParent.getElementsByTagName('*');
    for(var i = 0 ; i<elements.length;i++){
        if(elements[i].className == className){
            eles.push(elements[i]);
        }
    }
    return eles;
}

//获取最终样式
function getStyle(obj,attr){
    if(obj.currentStyle){
        return obj.currentStyle[attr];
    }else{
        return getComputedStyle(obj,false)[attr];
    }
}

function startMove(obj,json,fn){

    clearInterval(obj.timer);
    obj.timer = setInterval(function(){

        var flag = true; //假设动作是否全部达到期望值

        for(var attr in json) {
            // 取当前值
            var iCur = 0;
            if (attr == 'opacity') {
                iCur = Math.round(parseFloat(getStyle(obj, attr)) * 100)
            } else {
                iCur = parseInt(getStyle(obj, attr));
            }

            // 速度
            var speed = (json[attr] - iCur) / 8;
            speed = speed > 0 ? Math.ceil(speed) : Math.floor(speed);

            //判断是否结束
            if (iCur != json[attr]) {
                flag = false;
            }
            if (attr == 'opacity') {
                obj.style.opacity = (iCur + speed) / 100;
                obj.style.filter = 'alpha:(opacity=' + iCur + speed + ')';
            } else {
                obj.style[attr] = iCur + speed + 'px';
            }

        }

        if(flag){
            console.log(0);
            clearInterval(obj.timer);
            if (fn != undefined) {
                fn();
            }
        }
    },30)
}