要點一：
1 2 3 4 5 if(list_li.length>=1){ list.insertBefore(li,list_li[0]); }else{ list.appendChild(li); }從在前面插入新內容，如果沒有新內容，就是在後面插入新內容。
要點二：
1 2 var height=li.offsetHeight; li.style.height='0';取得li的高度，然後再li的高度設置為0,因為高度的變化是從0到現有高度。
要點三：
1 2 3 startrun(li,"height",height,function(){ startrun(li,"opacity","100"); })先是高度變化，再是透明度變化
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 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 <!DOCTYPE html> <html> <head> <meta charset="gb2312" /> <title>無標題文檔</title> <style> <!-- body,ul,li{margin:0; padding:0; font:12px/1.5 arial;} #list{width:400px; margin:10px auto;} #list li{list-style:none; padding:5px 0 ; overflow:hidden; border-bottom:1px dotted #ccc; filter:alpha(opacity:0); opacity:0; vertical-align:middle;} --> </style> <script> <!-- window.onload = function(){ var btn = document.getElementById("btn"); var con = document.getElementById("con"); var list = document.getElementById("list"); var list_li = list.getElementsByTagName("li"); btn.onclick = function(){ var li = document.createElement("li"); li.innerHTML = con.value; con.value=''; if(list_li.length>=1){ list.insertBefore(li,list_li[0]); }else{ list.appendChild(li); } var height=li.offsetHeight; li.style.height='0'; startrun(li,"height",height,function(){ startrun(li,"opacity","100"); }) } } function getstyle(obj,name){ if(obj.currentStyle){ return obj.currentStyle[name]; }else{ return getComputedStyle(obj,false)[name]; } } function startrun(obj,attr,target,fn){ clearInterval(obj.timer); obj.timer = setInterval(function(){ var cur = 0; if(attr == "opacity"){ cur = Math.round(parseFloat(getstyle(obj,attr))*100); }else{ cur = parseInt(getstyle(obj,attr)); } var speed = (target-cur)/8; speed = speed>0?Math.ceil(speed):Math.floor(speed); if(cur == target){ clearInterval(obj.timer); if(fn){ fn(); } }else{ if(attr == "opacity"){ obj.style.filter = "alpha(opacity="+(cur+speed)+")"; obj.style.opacity = (cur+speed)/100; }else{ obj.style[attr] = cur + speed + "px"; } } },30) } //--> </script> </head> <body> <textarea id="con" cols="50" rows="5"></textarea> <input id="btn" name="" type="button" value="發布"> <ul id="list"> </ul> </body> </html>