這裡可實現5個元素中隨便一個，鼠標移上去透明度漸漸增加，鼠標移出，透明度漸漸減小的效果。
要點一：
1 2 3 4 5 6 var speed = 0; if(target>obj.alpha){ speed = 5; }else{ speed = -5; }根據目標值和當時值的對比，來決定是正向還是負向速度。
要點二：
1 2 3 4 5 6 7 8 9 10 for(i=0; i<runs_li.length; i++){ runs_li[i].timer = null; runs_li[i].alpha = 30; runs_li[i].onmouseover = function(){ startrun(this,100); } runs_li[i].onmouseout = function(){ startrun(this,30); } }給每一個元素加上各自的透明度值，各自的透明度變化分開。
最後，上代碼：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>無標題文檔</title> <style> body,ul,li{margin:0; padding:0;} #runs{width:300px; margin:10px auto;} #runs li{width:80px; height:80px; background:#06c; list-style:none; float:left; margin:10px; display:inline; filter:alpha(opacity=30); opacity:0.3;} </style> <script> window.onload = function(){ var runs = document.getElementById("runs"); var runs_li = runs.getElementsByTagName("li"); var i=0; for(i=0; i<runs_li.length; i++){ runs_li[i].timer = null; runs_li[i].alpha = 30; runs_li[i].onmouseover = function(){ startrun(this,100); } runs_li[i].onmouseout = function(){ startrun(this,30); } } } function startrun(obj,target){ clearInterval(obj.timer); obj.timer = setInterval(function(){ var speed = 0; if(target>obj.alpha){ speed = 5; }else{ speed = -5; } if(obj.alpha == target){ clearInterval(obj.timer); }else{ obj.alpha = obj.alpha + speed; obj.style.filter = "alpha(opacity="+obj.alpha+")"; obj.style.opacity = obj.alpha/100; } },30) } </script> </head> <body> <ul id="runs"> <li>1</li> <li>2</li> <li>3</li> <li>4</li> <li>5</li> </ul> </body> </html>