javascript实现网页中涉及的简易运动（改变宽高、透明度、位置）

/* javascript简易运动  Move.action(dom对象,json格式属性值对，缓动参考值，回调方法) 示例：　var box = document.getElementById('Ele'); Move.action(box,{width:500,height:200,left:200,top:100,marginLeft:10,opacity:.5},5,function(){  console.log('end'); });*/var Move = { version: '1.5', //判断是否空对象 isEmptyObject: function(obj) { for (var attr in obj) { return false; } return true; }, //取CSS样式值 getStyle: function(obj, attr) { if (obj.currentStyle) { //IE return obj.currentStyle[attr]; } else { return getComputedStyle(obj, null)[attr]; } }, //运动 action: function(obj, json, sv, callback) { _this = this; //obj是否为空 if (_this.isEmptyObject(obj)) { return false; } //运动开始  clearInterval(obj.timer); obj.timer = setInterval(function() { var isAllCompleted = true, //假设全部运动都完成了 speed, //速度 attrValue, //当前值 targetV; //目标值 for (attr in json) { attrValue = _this.getStyle(obj, attr); switch (attr) {  case 'opacity':  attrValue = Math.round((isNaN(parseFloat(attrValue)) ? 1 : parseFloat(attrValue)) * 100);  speed = (json[attr] * 100 - attrValue) / (sv || 4);  targetV = json[attr] * 100;  break;  default:  attrValue = isNaN(parseInt(attrValue)) ? 0 : parseInt(attrValue);  speed = (json[attr] - attrValue) / (sv || 4);  targetV = json[attr]; } speed = speed > 0 ? Math.ceil(speed) : Math.floor(speed); //如果循环过程中存在尚未结束的运动，isAllCompleted为假 if (attrValue != targetV) {  isAllCompleted = false; } switch (attr) {  case 'opacity':  {  obj.style.filter = "alpha(opacity=" + (attrValue + speed) + ")";  obj.style.opacity = (attrValue + speed) / 100;  };  break;  default:  obj.style[attr] = attrValue + speed + 'px'; } } //所有循环结束后，只有当全部运动结束后（isAllCompleted=true）时才关闭定时器 if (isAllCompleted) { clearInterval(obj.timer); if (typeof callback === 'function') {  callback(); } } }, 30); }};