亲测必须将代码放在记事本中，改成html格式，在用IE运行（必须）
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title></title>
</head>
<script language="JavaScript">
function TextStreamTest(fname,Addname,n){
var fso,f,ts,s;
var ForRWA=0,ForReading=1,ForWriting=2,ForAppending=8;
var TristateUseDefault=-2,TristateTrue=-1,TristateFalse=0;
fso=new ActiveXObject("Scripting.FileSystemObject");
var s1=Addname.innerHTML;
if(fname.value!=""){
f=fso.GetFile(fname.value);
switch(n){
case 1:ForRWA=ForWriting;break;
case 2:ForRWA=ForAppending;break;
}
if(n>0){
ts=f.OpenAsTextStream(ForRWA,TristateUseDefault);
var s1=Addname.innerHTML;
ts.Write(s1);
s=ts.ReadLine();
ts.Close();
}
ts=f.OpenAsTextStream(ForReading,TristateUseDefault);
s=ts.ReadLine();
ts.Close();
}
return(s);
}
function run(n){
document.form3.textarea1.innerHTML=TextStreamTest(document.form5.text1,document.form4.textarea2,n);
}
</script>
<body>
<table width="392" border="1">
<tr>
<td height="24" colspan="2">
<form name="form5" method="post" action="">
文件路径:<input name="text1" type="textfield" value="E:\ss.txt" size="40">
</form>
</td>
</tr>
<tr>
<td width="207" height="163">
<form name="form3" method="post" action="">
<textarea name="textarea1" cols="30" rows="10"></textarea>
</form>
</td>
<td>
<form name="form4" method="post" action="">
<textarea name="textarea2" rows="10"></textarea>
</form>
</td>
</tr>
<tr>
<td height="28">
<form name="form1" method="post" action="">
<input type="button" name="Button" value="读取" onclick="run(0)">
</form>
</td>
<td>
<form name="form2" method="post" action="">
<input type="button" name="Submit2" value="写入" onclick="run(1)">
<input type="button" name="Button" value="添加" onclick="run(2)">
</form>
</td>
</tr>
</table>
</body>
</html>运行：
写入：即替换
添加：即在后面追加
