一个ajax表单验证实例，当用户鼠标点击输入框时在右边弹出提示信息，可根据自己的需求来自定义。
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<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<meta name="keywords" content="武鸣人网站,武鸣信息网,武鸣本地网,武鸣信息资源平台,减肥,健身,励志,励志语录,js特效,网页特效,www.wuming.ren">
<meta name="description" content="欢迎来到武鸣人信息资源平台，各种信息免费发布，资源共享合作共赢，分享互联网流行的励志语录经典短句，减肥健身健康小常识及打卡记录，收集各种js特效代码。">
<title>带提示信息ajax表单验证实例_武鸣人</title>
<style type="text/css">
form {
width:500px;
border:1px solid #ccc;
}
fieldset {
border:0;
padding:10px;
margin:10px;
position:relative;
}
label {
display:block;
font:normal 12px/17px verdana;
}
input {width:160px;}
span.hint {
font:normal 11px/14px verdana;
background:#eee;
color:#444;
border:1px solid #888;
padding:5px 5px 5px 40px;
width:250px;
position:absolute;
margin: -12px 0 0 14px;
display:none;
}
fieldset.welldone span.hint {
background:#9fd680;
border-color:#749e5c;
color:#000;
}
fieldset.kindagood span.hint {
background:#ffffcc;
border-color:#cc9933;
}
fieldset.welldone {
background:transparent;
}
fieldset.kindagood {
background:transparent;
}
</style>
<script type="text/javascript">
function checkuser_wuming(whatYouTyped) {
var fieldset = whatYouTyped.parentNode;
var txt = whatYouTyped.value;
if (txt.length > 5) {
fieldset.className = "welldone";
}
else {
fieldset.className = "";
}
}//武鸣人网站https://www.wuming.ren 网站很好记住，wuming.ren(武鸣拼音.ren域名后缀)
function checkps_wuming(whatYouTyped) {
var fieldset = whatYouTyped.parentNode;
var txt = whatYouTyped.value;
if (txt.length > 3 && txt.length < 8) {
fieldset.className = "kindagood";
} else if (txt.length > 7) {
fieldset.className = "welldone";
} else {
fieldset.className = "";
}
}//武鸣人网站https://www.wuming.ren 网站很好记住，wuming.ren(武鸣拼音.ren域名后缀)
function checkemail_wuming(whatYouTyped) {
var fieldset = whatYouTyped.parentNode;
var txt = whatYouTyped.value;
if (/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/.test(txt)) {
fieldset.className = "welldone";
} else {
fieldset.className = "";
}
}//武鸣人网站https://www.wuming.ren 网站很好记住，wuming.ren(武鸣拼音.ren域名后缀)
function addLoadEvent(func) {
var oldonload = window.onload;
if (typeof window.onload != 'function') {
window.onload = func;
} else {
window.onload = function() {
oldonload();
func();
}
}
}//武鸣人网站https://www.wuming.ren 网站很好记住，wuming.ren(武鸣拼音.ren域名后缀)
function prepareInputsForHints() {
var inputs = document.getElementsByTagName("input");
for (var i=0; i<inputs.length; i++){
inputs[i].onfocus = function () {
this.parentNode.getElementsByTagName("span")[0].style.display = "inline";
}
inputs[i].onblur = function () {
this.parentNode.getElementsByTagName("span")[0].style.display = "none";
}
}
}//武鸣人网站https://www.wuming.ren 网站很好记住，wuming.ren(武鸣拼音.ren域名后缀)
addLoadEvent(prepareInputsForHints);
</script>
</head>
<body>
<a href="https://www.wuming.ren">武鸣人</a>，各种信息资源免费发布，分享励志语录经典短句，减肥健身常识，各种js特效代码。网站很好记住，wuming.ren(武鸣拼音.ren域名后缀)<hr>
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<script type="text/javascript" src="https://www.wuming.ren/ad/tc.js"></script>
<script type="text/javascript" src="https://www.wuming.ren/ad/a.js"></script>
<form action="#" name="basicform" id="basicform" >
<fieldset>
<label for="username">用户名:</label>
<input type="text" id="username" onkeyup="checkuser_wuming(this);" />
<span class="hint">武鸣人提示您，用户名最低6位哦！</span>
</fieldset>
<fieldset>
<label for="password">密码:</label>
<input type="password" id="password" onkeyup="checkps_wuming(this);" />
<span class="hint">武鸣人提示您，密码需要4到8位哦！</span>
</fieldset>
<fieldset>
<label for="email">Email地址:</label>
<input type="text" id="email" onkeyup="checkemail_wuming(this);" />
<span class="hint">武鸣人提示您，请正确输入邮箱地址！</span>
</fieldset>
</form>
</body>
</html>