原生js简单实现jQuery的动画效果

// 动画效果
function startMove(obj,json,fn){
	clearInterval(obj.timer);
	var flag = true;
	obj.timer = setInterval(function(){
		for(var i in json){
			// 1.取当前值
			var oCur = 0;
			if(i == 'opacity'){
				oCur = Math.round(parseFloat(getStyle(obj,i))*100);
			}else{
				oCur = parseInt(getStyle(obj,i));
			}
			// 2.计算速度
			var speed = (json[i]-oCur)/20;
			speed = speed > 0 ? Math.ceil(speed):Math.floor(speed);
			console.log(speed)
			// 3.检测停止
			if(oCur != json[i]){
				flag = false;
			}else{
				flag = true;
			}
			if(i == 'opacity'){
				curNum = speed + oCur;
				obj.style.filter = 'alpha(opacity:'+curNum+')';
				obj.style.opacity = curNum/100;
			}else{
				obj.style[i] = oCur + speed +'px';
			}
		}
		if(flag){
			clearInterval(obj.timer);
			fn && fn();
		}
	},10)
}
// 获得css属性值
function getStyle(obj,attr){
	if(obj.currentStyle){
		return obj.currentStyle[attr];
	}else{
		return getComputedStyle(obj,false)[attr];
	}
}