#div1{ width: 200px;height: 200px; background: green; }

window.onload = function(){ var oDiv = document.getElementById('div1'); oDiv.onmouseover = function () { startMove(oDiv,'width',300,function () { startMove(oDiv,'height',function () { startMove(oDiv,'opacity',30); }); }); } oDiv.onmouseout = function () { startMove(oDiv,100,200,200); }); }); } } function getStyle(obj,attr){ return getComputedStyle ? getComputedStyle(obj,false)[attr] : obj.currentStyle[attr]; } function startMove(obj,fn) {//fn：执行下一个运动的函数 clearInterval(obj.timer); obj.timer = setInterval(function () { var objAttr = 0; if(attr == "opacity"){ objAttr = Math.round(parseFloat(getStyle(obj,attr))*100); }else{ objAttr = parseInt(getStyle(obj,attr)); } var iSpeed = (iTarget -objAttr)/10; iSpeed = iSpeed>0 ?Math.ceil(iSpeed):Math.floor(iSpeed); if(objAttr == iTarget){ clearInterval(obj.timer); if(fn){// 如果传了 “下一个运动的函数” 就执行 fn(); } }else{ if(attr == "opacity"){ obj.style.filter = 'alpha(opacity:'+(objAttr+iSpeed)+')'; obj.style.opacity = (objAttr+iSpeed)/100; }else{ obj.style[attr] = objAttr+iSpeed+'px'; } } },30); }