代码如下 正则表达式错误！！大哥们怎么改的啊？？？
function nm()
{
var a = document.getElementById("Names");
var b = /^\[a-z]|[A-Z]{4,12}$/; //我判断的是输入的是一个4到12位的英文小写或大写
if(b.test(a))
{
alert("正确!")
}
else
{
alert("错误！")
}
}
function nm()
{
var a = document.getElementById("Names");
var b = /^\[a-z]|[A-Z]{4,12}$/; //我判断的是输入的是一个4到12位的英文小写或大写
if(b.test(a))
{
alert("正确!")
}
else
{
alert("错误！")
}
}
var regx = /^([a-z]|[A-Z]){4,12}$/g;
var str = "abcd";
alert(regx.test(str));
<head>
<title>JS Test</title>
<script language="javascript">
function ff(obj,pid){
var value = obj.value;
if(value.match(/^([a-z]|[A-Z]){4,12}$/))
{
alert("success");
} else {
alert("failed")
}
document.getElementById(pid).innerHTML = value;
}
</script
</head>
<body>
<form>
<div id="text"></div>
<textarea id="findValue" onblur="ff(this, 'text');" ></textarea>
</form>
</body>
<html>
var a = document.getElementById("Names").value;
var b = /^[a-z]{4,12}$/i;
if(b.test(a)) {
alert("正确!");
} else {
alert("错误！")'
}
}
function nm(){
var a = document.getElementById("Names").value;
var b = /^[a-zA-Z]{4,12}$/;
if(b.test(a)) {
alert("正确!");
} else {
alert("错误！")'
}
}5楼的方法也挺好！！！
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title> new document </title>
</head>
<body>
<input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^[a-zA-Z]{4,12}$/.test(this.value));" />
</body>
</html>