正则表达式（检查用户名、密码、电话号码）

js代码：

<script type="text/javascript">
function checkU() { //检查用户名
var u = document.getElementById("userName");
var reU = document.getElementById("reUser");
if(u.value.length<2 || u.value.length>12){
u.focus();
reU.innerHTML = "用户名长度在2-12字符之间";
}
else {
reU.innerHTML = "";
}
}

function checkP(){ //检查密码格式
var p = document.getElementById("password");
var rePwd = document.getElementById("rePwd");
var reg = /^\w{6,18}$/;
if(!reg.test(p.value)){
p.focus();
rePwd.innerHTML = "密码由6-18位的数字、字母、下划线组成";
}else {
rePwd.innerHTML = "";
}
}

function checkT() { //检查手机号格式
var t = document.getElementById("tel");
var reTel = document.getElementById("reTel");
var reg = /^1[3578][0-9]{9}$/;
if(!reg.test(t.value)){
t.focus();
reTel.innerHTML = "请输入11位有效手机号";
}
else {
reTel.innerHTML = "";
}
}
</script>

jsp代码：

<div>
用户名：<input name="userName" type="text" id="userName" class="text" onblur="checkU()"/></div>
<div id = "reUser" style="color: red;font-size: 10px;"></div>

<div>
密   码：<input name="password" type="password" id="password" class="text" onblur="checkP()" /></div>
<div id="rePwd" style="color: red;font-size: 10px"></div>

<div>
电   话：<input name="telephone" id="tel" type="text" class="text" onblur="checkT()">
</div>
<div id = "reTel" style="color: red;font-size: 10px"></div>

<div>
地   址：<input name="address" type="text" class="text">
</div>
<div align="right">
<input type="submit" value="注册">
</div>