邮箱自动完成的效果在网站上大多都看过，但是质量参差不齐，今天突然在网上看到一篇博客，感觉这个插件很好，就想来写一下分享给大家！
效果图如下！
完整demo代码如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>邮箱地址自动完成功能</title>
<meta http-equiv="content-type" content="text/html;charset=gb2312">
<style>
.demo p {width:1000px; margin-left:auto; margin-right:auto;}
.input{padding:12px; width:300px; border:1px solid #c2c2c2; border-radius:4px; box-shadow:0 0 1px #fff, inset 0 0 2px rgba(0,0,0,.15); background-color:#F2F2F2; font-size:14px;}
.emailist{border:1px solid #bdbdbd; border-radius: 4px; background-color:#fff; color:#666; font-size:14px; list-style-type:0; padding:0; margin:0; overflow:hidden;}
.emailist li{padding:2px 11px; cursor:pointer;}
.emailist .on, .emailist li:hover{background-color:#eee;}
</style>
</head>
<body>
<div class="demo">
<p><input type="email" class="input inputMailList" name="email" placeholder="请输入邮箱" required autofocus autocomplete="off"></p>
</div>
</body>
</html>
<script src="js/jquery-1.6.2.min.js"></script>
<script src="js/jquery.mailAutoComplete-4.0.js"></script>
<script type="text/javascript">
$(".inputMailList").mailAutoComplete();//使用方法
</script>
js实现效果代码（jquery.mailAutoComplete-4.0.js）如下：
(function($) {
$.fn.mailAutoComplete = function(options) {
var defaults = {
className: "emailist",
email: ["qq.com","gmail.com","126.com","163.com","hotmail.com","yahoo.com","yahoo.com.cn","live.com","sohu.com","sina.com"], //邮件数组
zIndex: 11
};
// 最终参数
var params = $.extend({}, defaults, options || {});
// 是否现代浏览器
var isModern = typeof window.screenX === "number", visibility = "visibility";
// 键值与关键字
var key = {
"up": 38,
"down": 40,
"enter": 13,
"esc": 27,
"tab": 9
};
// 组装HTML的方法
var fnEmailList = function(input) {
var htmlEmailList = '', arrValue = input.value.split("@"), arrEmailNew = [];
$.each(params.email, function(index, email) {
if (arrValue.length !== 2 || arrValue[1] === "" || email.indexOf(arrValue[1].toLowerCase()) === 0) {
arrEmailNew.push(email);
}
});
$.each(arrEmailNew, function(index, email) {
htmlEmailList = htmlEmailList + '<li'+ (input.indexSelected===index? ' class="on"':'') +'>'+ arrValue[0] + "@" + email +'</li>';
});
return htmlEmailList;
};
// 显示还是隐藏
var fnEmailVisible = function(ul, isIndexChange) {
var value = $.trim(this.value), htmlList = '';
if (value === "" || (htmlList = fnEmailList(this)) === "") {
ul.css(visibility, "hidden");
} else {
isIndexChange && (this.indexSelected = -1);
ul.css(visibility, "visible").html(htmlList);
}
};
return $(this).each(function() {
this.indexSelected = -1;
// 列表容器创建
var element = this;
var eleUl = $('<ul></ul>').css({
position: "absolute",
marginTop: element.offsetHeight,
minWidth: element.offsetWidth - 2,
visibility: "hidden",
zIndex: params.zIndex
}).addClass(params.className).bind("click", function(e) {
var target = e && e.target;
if (target && target.tagName.toLowerCase() === "li") {
$(element).val(target.innerHTML).trigger("input");
$(this).css(visibility, "hidden");
element.focus(); // add on 2013-11-20
}
});
$(this).before(eleUl);
// IE6的宽度
if (!window.XMLHttpRequest) { eleUl.width(element.offsetWidth - 2); }
// 不同浏览器的不同事件
isModern? $(this).bind("input", function() {
fnEmailVisible.call(this, eleUl, true);
}): element.attachEvent("onpropertychange", function(e) {
if (e.propertyName !== "value") return;
fnEmailVisible.call(element, eleUl, true);
});
$(document).bind({
"click": function(e) {
var target = e && e.target, htmlList = '';
if (target == element && element.value && (htmlList = fnEmailList(element, params.email))) {
eleUl.css(visibility, "visible").html(htmlList);
} else if (target != eleUl.get(0) && target.parentNode != eleUl.get(0)) {
eleUl.css(visibility, "hidden");
}
},
"keydown": function(e) {
var eleLi = eleUl.find("li");
if (eleUl.css(visibility) === "visible") {
switch (e.keyCode) {
case key.up: {
element.indexSelected--;
if (element.indexSelected < 0) {
element.indexSelected = -1 + eleLi.length;
}
e.preventDefault && e.preventDefault();
break;
}
case key.down: {
element.indexSelected++;
if (element.indexSelected >= eleLi.length) {
element.indexSelected = 0;
}
e.preventDefault && e.preventDefault();
break;
}
case key.enter: {
e.preventDefault();
eleLi.get(element.indexSelected) && $(element).val(eleLi.eq(element.indexSelected).html());
eleUl.css("visibility", "hidden");
break;
}
case key.tab: case key.esc: {
eleUl.css("visibility", "hidden");
break;
}
}
if (element.indexSelected !== -1) {
eleUl.html(fnEmailList(element));
}
}
}
});
});
};
})(jQuery);
个人觉得这个插件比较好用，而且代码很精简！