原生js实现下拉框功能（支持键盘事件）

话不多说，请看代码：

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>倒计时-多种格式调用-原生js封装</title>
 <link rel="shortcut icon" href="../public/image/favicon.ico" type="images/x-icon"/>
 <link rel="icon" href="../public/image/favicon.png" type="images/png"/>
 <link rel="stylesheet" type="text/css" href="../public/style/cssreset-min.css">
 <link rel="stylesheet" type="text/css" href="../public/style/common.css">
 <style type="text/css">
 /*公共*/
 html{
 height:100%;
 }
 body, div, dl, dt, dd, ul, ol, li, h1, h2, h3, h4, h5, h6, pre, code, form, fieldset, legend, input, textarea, p, blockquote, th, td {
 margin: 0;
 padding: 0
 }
 ol, ul {
 list-style: none
 }
 body{
 position: relative;
 min-height:100%;
 font-size:14px;
 font-family: Tahoma, Verdana,"Microsoft Yahei";
 color:#333;
 }
 a{
 text-decoration: none;
 color:#333;
 }
 .header{
 width: 960px;
 padding-top: 15px;
 margin: 0 auto;
 line-height: 30px;
 text-align: right;
 }
 .header a{
 margin: 0 5px;
 }
 .main{
 width:960px;
 margin: 50px auto 0;
 }
 .code{
 border:1px dashed #e2e2e2;
 padding:10px 5px;
 margin-bottom:25px;
 }
 pre {
 font-family: "Microsoft Yahei",Arial,Helvetica;
 white-space: pre-wrap; /*css-3*/ 
 white-space: -moz-pre-wrap; /*Mozilla,since1999*/ 
 white-space: -pre-wrap; /*Opera4-6*/ 
 white-space: -o-pre-wrap; /*Opera7*/ 
 word-wrap: break-word; /*InternetExplorer5.5+*/
 }
 .example{
 padding-top:40px;
 margin-bottom:90px;
 }
 .example .call{
 padding:18px 5px;
 background:#f0f5f8;
 }
 .example h2{
 padding-top:20px;
 margin-bottom:7px;
 }
 .example table {
 width:100%;
 table-layout:fixed;
 border-collapse: collapse;
 border-spacing: 0;
 border: 1px solid #cee1ee;
 border-left: 0;
 }
 .example thead {
 border-bottom: 1px solid #cee1ee;
 background-color: #e3eef8;
 }
 .example tr {
 line-height: 24px;
 font-size: 13px;
 }
 .example tr:nth-child(2n) {
 background-color: #f0f5f8;
 }
 .example tr th,.example tr td {
 border-left: 1px solid #cee1ee;
 word-break: break-all;
 word-wrap: break-word;
 padding:0 10px;
 font-weight: normal;
 }
 .example tr th {
 color: #555;
 padding-top: 2px;
 padding-bottom: 2px;
 text-align: left;
 }
 /*公共*/
 .select-container {
 width: 186px;
 margin: 80px 0;
 position: relative;
 z-index: 10000;
 }
 .select-container .select-pose {
 width: 150px;
 height: 24px;
 line-height: 24px;
 display: block;
 color: #807a62;
 cursor: pointer;
 font-style: normal;
 padding-left: 4px;
 padding-right: 30px;
 border: 1px solid #333333; /* background: url(xjt.png) no-repeat right center; */
 }
 .select-pose:before {
 content: '';
 position: absolute;
 right: 7px;
 bottom: 7px;
 width: 0;
 height: 0;
 border-width: 4px;
 border-style: solid;
 border-color: #888 transparent transparent transparent;
 transition: all 0.2s;
 -webkit-transition: all 0.2s;
 -moz-transition: all 0.2s;
 -o-transition: all 0.2s;
 -ms-transition: all 0.2s;
 transform-origin: 50% 25%;
 -ms-transform-origin: 50% 25%;
 -moz-transform-origin: 50% 25%;
 -webkit-transform-origin: 50% 25%;
 -o-transform-origin: 50% 25%;
 }
 .extended.select-pose:before {
 transform: rotate(180deg);
 -webkit-transform: rotate(180deg);
 -moz-transform: rotate(180deg);
 -o-transform: rotate(180deg);
 -ms-transform: rotate(180deg);
 }
 .select-container .select-content {
 width: 184px;
 border: 1px solid #333333;
 background-color: #ffffff;
 position: absolute;
 z-index: 20000;
 margin-top: -1px;
 display: none;
 overflow: hidden;
 }
 .select-list{
 cursor: pointer;
 height: 24px;
 line-height: 24px;
 padding-left: 10px;
 }
 </style>
 <script type="text/javascript">
 /*封装代码*/
 (function() {
 var Select = function(el, opts) {
 var self = this;
 var defaults = {
 before: '#fff',
 after:'#ccc'
 }
 opts = opts || {};
 for (var w in defaults) {
 if ("undefined" == typeof opts[w]) {
 opts[w] = defaults[w];
 }
 }
 this.params = opts;
 this.container = r(el);

 if (this.container.length > 1) {
 var x = [];
 return this.container.each(function() {
 x.push(new Select(this, opts))
 }), x
 }
 this.containers=this.container[0];
 this.pose=this.container.find(".select-pose")[0];
 this.content=this.container.find(".select-content")[0];
 this.list=this.container.find(".select-list");
 this.index=-1;
 this.init();
 }
 Select.prototype = {
 //初始化
 init: function() {
 var self = this;
 this.page();
 this.event();
 this.mover();
 },
 event:function(){
 var self = this;
 self.pose.addEventListener('click', function(e) {
 e = e || window.event;
 e.stopPropagation ? e.stopPropagation() : e.cancelBubble = true;
 var oSrc = e.srcElement || e.target;
 if(oSrc.className.indexOf('extended') > -1){
 self.resetM();
 }else{
 oSrc.classList.add("extended");
 self.content.style.display = "block";
 }
 }, false);
 },
 //鼠标经过list
 mover:function(){
 var self = this;
 var list=this.list;
 for (var i = 0; i < list.length; i++) {
 !function(i){
 list[i].addEventListener('mouseover', function(e) {
 self.resetA();
this.style.background = self.params.after;
 self.index=i;
 }, false);
 }(i)
 list[i].addEventListener('click', function(e) {
 self.pose.innerHTML = this.innerHTML;
 }, false);
 }
 },
 resetA:function(){
 var self = this;
 var list=this.list;
 for (var i = 0; i < list.length; i++) {
 list[i].style.background = self.params.before;
 }
 },
 resetM:function(){
 var self = this;
 self.content.style.display = "none";
 self.pose.classList.remove("extended");
 self.resetA();
 },
 // 点击页面空白处时
 page:function(){
 var self = this;
 document.addEventListener('click', function(e) {
 self.resetM();
 }, false);
 document.addEventListener('keydown', function(e) {
 e = e || window.event;
 var keyVel=e.keyCode;
 if (keyVel == 38 || keyVel == 37) {
 e.preventDefault ? e.preventDefault() : e.returnValue = false;//取消事件默认行为
 self.index--;
 if (self.index < 0) {
 self.index = self.list.length-1;
 }
 self.resetA();
 self.list[self.index].style.backgroundColor = self.params.after;
 } else if (keyVel == 39 || keyVel == 40) {
 e.preventDefault ? e.preventDefault() : e.returnValue = false;//取消事件默认行为
 self.index++;
 if (self.index > self.list.length-1) {
 self.index = 0;
 }
 self.resetA();
 self.list[self.index].style.backgroundColor = self.params.after;
 }else if(keyVel == 13 && self.index != -1){
 e.preventDefault ? e.preventDefault() : e.returnValue = false;
 self.pose.innerHTML = self.list[self.index].innerHTML;
 self.index = -1;
 self.resetA();
 self.resetM();
 }
 }, false);
 },
 }
 var r = (function() {
 var e = function(e) {
 var a = this,
 t = 0;
 for (t = 0; t < e.length; t++) {
 a[t] = e[t];
 }
 return a.length = e.length, this
 };
 e.prototype = {
 addClass: function(e) {
 if ("undefined" == typeof e) return this;
 for (var a = e.split(" "), t = 0; t < a.length; t++)
 for (var r = 0; r < this.length; r++) this[r].classList.add(a[t]);
 return this
 },
 each: function(e) {
 for (var a = 0; a < this.length; a++) e.call(this[a], a, this[a]);
 return this
 },
 html: function(e) {
 if ("undefined" == typeof e) return this[0] ? this[0].innerHTML : void 0;
 for (var a = 0; a < this.length; a++) this[a].innerHTML = e;
 return this
 },
 find: function(a) {
 for (var t = [], r = 0; r < this.length; r++)
 for (var i = this[r].querySelectorAll(a), s = 0; s < i.length; s++) t.push(i[s]);
 return new e(t)
 },
 append: function(a) {
 var t, r;
 for (t = 0; t < this.length; t++)
 if ("string" == typeof a) {
 var i = document.createElement("div");
 for (i.innerHTML = a; i.firstChild;) this[t].appendChild(i.firstChild)
 } else if (a instanceof e)
 for (r = 0; r < a.length; r++) this[t].appendChild(a[r]);
 else this[t].appendChild(a);
 return this
 },
 }
 var a = function(a, t) {
 var r = [],
 i = 0;
 if (a && !t && a instanceof e) {
 return a;
 }
 if (a) {
 if ("string" == typeof a) {
 var s, n, o = a.trim();
 if (o.indexOf("<") >= 0 && o.indexOf(">") >= 0) {
 var l = "div";
 for (0 === o.indexOf("<li") && (l = "ul"), 0 === o.indexOf("<tr") && (l = "tbody"), (0 === o.indexOf("<td") || 0 === o.indexOf("<th")) && (l = "tr"), 0 === o.indexOf("<tbody") && (l = "table"), 0 === o.indexOf("<option") && (l = "select"), n = document.createElement(l), n.innerHTML = a, i = 0; i < n.childNodes.length; i++) r.push(n.childNodes[i])
 } else
 for (s = t || "#" !== a[0] || a.match(/[ .<>:~]/) ? (t || document).querySelectorAll(a) : [document.getElementById(a.split("#")[1])], i = 0; i < s.length; i++) s[i] && r.push(s[i])
 } else if (a.nodeType || a === window || a === document) {
 r.push(a);
 } else if (a.length > 0 && a[0].nodeType) {
 for (i = 0; i < a.length; i++) {
 r.push(a[i]);
 }
 }
 }
 return new e(r)
 };
 return a;
 }())
 window.select = Select;
 })()
 /*封装代码*/
 </script>
</head>
<body>
 <div class="header">
 <a href="https://github.com/huanghanzhilian/widget" target="_blank">项目地址</a>
 <a href="/widget/">返回首页</a>
 </div>
 <div class="main">
 <div class="select-container" id="select1">
 <cite class="select-pose">请选择分类</cite>
 <ul class="select-content">
 <li class="select-list">选项一</li>
 <li class="select-list">选项二</li>
 <li class="select-list">选项三</li>
 <li class="select-list">选项四</li>
 </ul>
 </div>
 <script type="text/javascript">
 new select("#select1");
 </script>
 <div class="code">
 <p>
 支持键盘事件,执行默认参数,鼠标点击分类显示,鼠标经过list执行默认参数
 </p>
 <p>new select("#select1");</p>
 </div>
 <div class="example">
 <div class="call">
 <h1>调用方法：</h1>
 <p>new select(selector,{options});</p>
 </div>
 <h2>options参数</h2>
 <table>
 <thead>
 <tr>
 <th width="150">参数</th>
 <th width="100">默认值</th>
 <th>说明</th>
 </tr>
 </thead>
 <tbody>
 <tr>
 <td>before</td>
 <td>'#fff'</td>
 <td>鼠标经过list初始化颜*值</td>
 </tr>
 <tr>
 <td>after</td>
 <td>'#ccc'</td>
 <td>鼠标经过list颜*值</td>
 </tr>
 </tbody>
 </table>
 </div>
 </div>
</body>
</html>

以上就是本文的全部内容，希望本文的内容对大家的学习或者工作能带来一定的帮助，同时也希望多多支持！

# js # 下拉框 # 原生 # javascript 键盘事件总结推荐 # js监听键盘事件示例代码 # js和jquery实现监听键盘事件示例代码 # js捕捉键盘事件和按键键值的方法 # js鼠标、键盘事件实例代码 # 浅谈js键盘事件全面控制 # js中获取键盘事件的简单实现方法 # js中键盘事件实例简析 # javascript中键盘事件用法实例分析 # Javascript 键盘事件的组合使用实现代码 # JavaScript键盘事件常见用法实例分析 # 鼠标 # 请选择 # 多说 # 首页 # 倒计时 # 默认值 # 鼠标点击 # 空白处 # auto # line # width # top # dashed # border # align # main # size # family # px # position

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原生js实现下拉框功能（支持键盘事件）

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