本文分享一个由原生JS实现的注册或登录时，输入邮箱时下拉提示效果，效果如下：
实现代码如下：
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>原生JS实现登录框提示</title>
<style>
* {
margin: 0;
padding: 0;
}
body {
font: 12px/1.125 Arial, Helvetica, sans-serif;
}
li {
list-style: none;
}
#login {
width: 252px;
height: 385px;
/* 彩色背景图 */
background: url(images/0.jpg) no-repeat;
margin: 20px auto;
position: relative;
}
.detail {
margin: 0 0 5px 30px;
position: relative;
top: 110px;
}
.detail input {
color: #999999;
border: 1px solid #74C8E5;
border-radius: 3px 3px 3px 3px;
height: 15px;
line-height: 14px;
padding: 8px 5px 7px;
width: 184px;
}
#suggest {
background: none repeat scroll 0 0 #FFFFFF;
border: 1px solid #CCCCCC;
left: 30px;
margin: 0;
overflow: hidden;
padding: 0;
position: absolute;
text-align: left;
top: 142px;
visibility: visible;
width: 194px;
z-index: 1;
display: none;
}
.note,
.item {
clear: both;
color: #999999;
cursor: pointer;
font-size: 12px;
height: 20px;
line-height: 20px;
list-style: none outside none;
margin: 0 1px;
padding: 0 5px;
white-space: nowrap;
}
.active {
white-space: nowrap;
clear: both;
color: rgb(153, 153, 153);
cursor: pointer;
font-size: 12px;
height: 20px;
line-height: 20px;
list-style: none outside none;
margin: 0pt 1px;
padding: 0pt 5px;
background: none repeat scroll 0% 0% rgb(232, 244, 252);
}
</style>
<script>
//页面加载完成时
window.onload = function () {
//创建构造函数
var s1 = new Suggest();
//初始化
s1.init();
};
//构造函数
function Suggest() {
//获取用户名输入框
this.oInput = document.getElementById('input1');
//获取下拉列表提示框
this.oUl = document.getElementById('suggest');
//获取下拉列表项
this.aLi = this.oUl.getElementsByTagName('li');
}
//为构造函数添加原型方法
Suggest.prototype = {
//初始化时
init: function () {
// 输入改变时
this.toChange();
// 光标移开时
this.toBlur();
},
//边续触发改变时
toChange: function () {
//添加连续输入事件，并兼容各浏览器
var ie = !-[1,];
var This = this;
if (ie) {
this.oInput.onpropertychange = function () {
//防止在IE下输入值为空的时候，触发下拉提示框
if (This.oInput.value == '') {
This.tips();
return;
}
//显示下拉列表框
This.thowUl();
//显示提示
This.tips();
//输入时的默认选中
This.sel(0);
};
} else {
this.oInput.oninput = function () {
//显示下拉列表框
This.thowUl();
//显示提示
This.tips();
//输入时的默认选中
This.sel(0);
};
}
},
//显示下拉列表框
thowUl: function () {
this.oUl.style.display = 'block';
},
//光标移开时，隐藏下拉担示框
toBlur: function () {
var This = this;
this.oInput.onblur = function () {
This.oUl.style.display = 'none';
};
},
//输入时，提示内空相应改变
tips: function () {
var value = this.oInput.value;
//定义邮箱正则（@加上@后面输入的值加空格)
var re = new RegExp('@' + value.substring(value.indexOf('@') + 1) + '');
//初始化显示下拉列表
//防止清空输入后不显示下拉列表
for (var i = 1; i < this.aLi.length; i++) {
this.aLi[i].style.display = 'block';
this.aLi[i].bBtn = true;
}
if (re.test(value)) {
//获取所有li的自定义属性(除开第一个)
for (var i = 1; i < this.aLi.length; i++) {
var oEmail = this.aLi[i].getAttribute('email');
//为选中的第1个li直接赋值
if (i == 1) {
//将输入值赋给li
this.aLi[i].innerHTML = value;
} else {
if (re.test(oEmail)) {
this.aLi[i].style.display = 'block';
this.aLi[i].bBtn = true;
} else {
this.aLi[i].style.display = 'none';
this.aLi[i].bBtn = false;
}
}
}
} else {
//获取所有li的自定义属性(除开第一个)
for (var i = 1; i < this.aLi.length; i++) {
var oEmail = this.aLi[i].getAttribute('email');
//如果获取的oEmail值为空时，即为第一个时
if (!oEmail) {
//将输入值赋给li
this.aLi[i].innerHTML = value;
} else {
//li的内容为输入值加上其属性值
this.aLi[i].innerHTML = value + oEmail;
}
}
}
},
//提示列表项选中方法
sel: function (iNow) {
var This = this;
var arr = [];
//选中一个提示后，重新输入时，将选中项还原为默认样式
for (var i = 1; i < this.aLi.length; i++) {
this.aLi[i].className = 'item';
if (this.aLi[i].bBtn) {
arr.push(this.aLi[i]);
}
}
//当输入内容为空时
if (this.oInput.value == '') {
//样式为item
arr[iNow].className = 'item';
//当输入内容不为空时
} else {
//样式为active
arr[iNow].className = 'active';
}
//为所有的下拉提示添加鼠标移入事件
for (var i = 1; i < arr.length; i++) {
arr[i].index = i;
//鼠标移入时
arr[i].onmouseover = function () {
//将所有li的样式还原为默认样式
for (var i = 1; i < This.aLi.length; i++) {
This.aLi[i].className = 'item';
}
//为当前选项添加样式为active
this.className = 'active';
iNow = this.index;
};
//鼠标点击时，将当前的提示选项内容替换为输入值
arr.onmousedown = function () {
This.oInput.value = this.innerHTML;
};
}
//添加键盘事件
document.onkeydown = function (ev) {
//做事件兼容
var ev = ev || window.event;
//上
if (ev.keyCode == 38) {
if (iNow == 0) {
iNow = arr.length - 1;
} else {
iNow--;
}
for (var i = 1; i < This.aLi.length; i++) {
This.aLi[i].className = 'item';
}
arr[iNow].className = 'active';
//下
} else if (ev.keyCode == 40) {
//当iNow为最后一个时，赋值为0
if (iNow == arr.length - 1) {
iNow = 0;
} else {
iNow++;
}
//清空所有li样式为默认样式
for (var i = 1; i < This.aLi.length; i++) {
This.aLi[i].className = 'item';
}
//为当前选项添加active样式
arr[iNow].className = 'active';
//回车
} else if (ev.keyCode == 13) {
//将当前的提示选项内容替换为输入值
This.oInput.value = arr[iNow].innerHTML;
//将光标移开输入框，关闭下拉列表项
This.oInput.blur();
}
};
}
};
</script>
</head>
<body>
<div id="login">
<div class="detail">
<input id="input1" type="text" maxlength="128" placeholder="邮箱/会员帐号/手机号" autocomplete="off"
node-type="loginname" class="name" tabindex="1" name="loginname">
</div>
<div class="detail">
<input type="password" maxlength="24" placeholder="请输入密码" node-type="password" class="pass" tabindex="2"
name="password">
</div>
<ul id="suggest">
<li class="note">请选择邮箱类型</li>
<li email="" class="item"></li>
<li email="@sina.com" class="item">@sina.com</li>
<li email="@163.com" class="item">@163.com</li>
<li email="@qq.com" class="item">@qq.com</li>
<li email="@126.com" class="item">@126.com</li>
<li email="@vip.sina.com" class="item">@vip.sina.com</li>
<li email="@sina.cn" class="item">@sina.cn</li>
<li email="@hotmail.com" class="item">@hotmail.com</li>
<li email="@gmail.com" class="item">@gmail.com</li>
<li email="@sohu.com" class="item">@sohu.com</li>
<li email="@yahoo.cn" class="item">@yahoo.cn</li>
<li email="@139.com" class="item">@139.com</li>
<li email="@wo.com.cn" class="item">@wo.com.cn</li>
<li email="@189.cn" class="item">@189.cn</li>
</ul>
</div>
</body>
</html>
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