<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <title></title> <style> #img1 { height:300px; width:300px; margin:30px auto; filter:alpha(opacity=30); opacity:0.3; } </style> <script type="text/javascript"> window.onload = function () { var oImg = document.getElementById(‘img1‘); oImg.onmouseover = function () { StarMove(100); } oImg.onmouseout = function () { StarMove(30); } } var timer = null; var alpha = 30; function StarMove(iTarget) { var oImg = document.getElementById(‘img1‘); var iSpeed = 0; if (alpha < iTarget) { iSpeed = 5; } else { iSpeed = -5; } clearInterval(timer); timer = setInterval(function () { alpha += iSpeed; if (alpha == iTarget) { clearInterval(timer); } else { oImg.style.filter = "alpha(opacity=" + alpha + ")"; oImg.style.opacity = alpha / 100; } }, 30); } </script> </head> <body> <img id="img1" src="images/02.jpg" alt="" /> </body> </html>
原文：http://www.cnblogs.com/juexin/p/4057267.html