经常使用的js代码片断

时间 2019-11-08

原文原文链接

1.单选框/手风琴

1 <script>
2         $(document).ready(function(){
3             $("dd").on("click",function(){
4                 var $this = $(this);
5                 $("dd").removeClass("selected");
6                 $this.addClass("selected");
7             })
8         })
9     </script>

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2.复选框

 1 function checkListTwo(){    //点击变换效果
 2             var li = document.getElementById("checkList").getElementsByTagName("li");
 3             for(var i=0;i<li.length;i++){
 4                 li[i].onclick = function(){
 5                     if(this.className == 'selected'){
 6                         this.className = null;  //单击若判断已有类,再次点击选中会清空class
 7                     }else{
 8                         this.className = 'selected';
 9                     }
10                 }
11             }
12         }

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3.多级导航菜单

 1 <script>
 2 window.onload=function(){
 3     var aLi=document.getElementsByTagName('li');
 4     
 5     for(var i=0; i<aLi.length; i++){
 6         aLi[i].onmouseover=function(){
 7             //鼠标通过一级菜单，二级菜单动画下拉显示出来
 8             var subNav=this.getElementsByTagName("ul")[0];
 9             subNav.className='';
10             //alert(subNav.innerHTML);
11         }
12         //鼠标离开菜单，二级菜单动画收缩起来。        
13         aLi[i].onmouseout=function(){
14             var subNav=this.getElementsByTagName("ul")[0];
15             subNav.className="subNav";
16         }    
17     }
18 }
19 </script>

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4.获取时间，把获取到的毫秒数转换成咱们须要的时间格式便可

 1 function getFormatTime(time) {
 2         var time = time  0;
 3  
 4         var h = parseInt(time/3600),
 5             m = parseInt(time%3600/60),
 6             s = parseInt(time%60);
 7         h = h < 10 ? "0"+h : h;
 8         m = m < 10 ? "0"+m : m;
 9         s = s < 10 ? "0"+s : s;
10  
11         return h+":"+m+":"+s;
12     }

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5.小时钟显示

 1 <!doctype html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5 
 6     <title>Date</title>
 7 </head>
 8 <body onload="startTime()">
 9     <script>
10 //        var date = new Date();
11 //        document.write(date.getFullYear()+"<br />");//年
12 //        document.write(date.getMonth()+"<br />"); //月要加1
13 //        document.write(date.getDate()+"<br />");//日期
14 //        document.write(date.getDay()+"<br />");  //星期
15 //        document.write(date.getHours()+"<br />");//时
16 //        document.write(date.getMinutes()+"<br />");//分
17 //        document.write(date.getSeconds()+"<br />"); //秒
18 
19         function startTime() {
20             var today = new Date();
21             var h = today.getHours();
22             var m = today.getMinutes();
23             var s = today.getSeconds();
24             m = checkTime(m);
25             s = checkTime(s);
26             document.getElementById("timetxt").innerHTML = h+":"+m+":"+s;
27             t = setTimeout(function(){
28                 startTime();
29             },500);
30         }
31         function checkTime(i){
32             if(i<10){
33               i = "0"+i;
34             }
35             return i;
36         }
37     </script>
38     <div id="timetxt"></div>
39 </body>
40 </html>

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6.小写转大写

 1 <html>
 2 
 3 <head>
 4 <script type="text/javascript">
 5 function upperCase(x)
 6 {
 7 var y=document.getElementById(x).value
 8 document.getElementById(x).value=y.toUpperCase()
 9 }
10 </script>
11 </head>
12 
13 <body>
14 
15 Enter your name: <input type="text" id="fname" onchange="upperCase(this.id)">
16 
17 </body>
18 </html>

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7.禁止用户输入数字

 1 <!DOCTYPE html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>Document</title>
 6 </head>
 7 <body>
 8 <form>
 9     Type some text (numbers not allowed):
10     <input type="text" onkeydown="return noNumbers(event)" />
11 </form>
12 
13 <script type="text/javascript">
14 function noNumbers(e)
15 {
16     var keynum;
17     var keychar;
18     var numcheck;
19 
20 if(window.event) // IE
21     {
22     keynum = e.keyCode;
23     }
24 else if(e.which) // Netscape/Firefox/Opera
25     {
26     keynum = e.which
27     }
28     keychar = String.fromCharCode(keynum)
29     numcheck = /\d+/
30     return !numcheck.test(keychar)      //把这个！去掉就是不能限制字母了
31 }
32 </script>
33 </body>
34 </html>

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8.Web SQL浏览器端数据库

<html>
   <head>
      <meta charset="UTF-8">  
       <title>Web SQL</title> 
      <script type="text/javascript">
      
         var db = openDatabase('mydb', '1.0', 'Test DB', 2 * 1024 * 1024);
         var msg;
         
         db.transaction(function (tx) {
            tx.executeSql('CREATE TABLE IF NOT EXISTS LOGS (id unique, log)');
            tx.executeSql('INSERT INTO LOGS (id, log) VALUES (1, "lucas")');
            tx.executeSql('INSERT INTO LOGS (id, log) VALUES (2, "www.baidu.com")');
            msg = '<p>数据表已建立，且插入了两条数据。</p>';
            document.querySelector('#status').innerHTML =  msg;
         });

         db.transaction(function (tx) {
              tx.executeSql('DELETE FROM LOGS  WHERE id=1');
              msg = '<p>删除 id 为 1 的记录。</p>';
              document.querySelector('#status').innerHTML +=  msg;
         });

         db.transaction(function (tx) {
             tx.executeSql('UPDATE LOGS SET log=\'baidu.com\' WHERE id=2');
              msg = '<p>更新 id 为 2 的记录。</p>';
              document.querySelector('#status').innerHTML +=  msg;
         });

         db.transaction(function (tx) {
            tx.executeSql('SELECT * FROM LOGS', [], function (tx, results) {
               var len = results.rows.length, i;
               msg = "<p>查询记录条数: " + len + "</p>";
               document.querySelector('#status').innerHTML +=  msg;
               
               for (i = 0; i < len; i++){
                  msg = "<p><b>" + results.rows.item(i).log + "</b></p>";
                  document.querySelector('#status').innerHTML +=  msg;
               }
            }, null);
         });
         
      </script>
      
   </head>
   
   <body>
      <div id="status" name="status">状态信息</div>
   </body>
   
</html>

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9.一个增删demo

 1 <!DOCTYPE html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>一个增删demo</title>
 6 </head>
 7 <body>
 8     <input type="text" id="text">
 9     <input type="button" value="添加" id="button">
10     <ul>
11         <li>第1个<button class="btn" id="1">删除</button></li>
12         <li>第2个<button class="btn" id="2">删除</button></li>
13         <li>第3个<button class="btn" id="3">删除</button></li>
14     </ul>
15     <script>
16             var button = document.getElementById("button");
17             var text = document.getElementById("text");
18             var ul = document.getElementsByTagName("ul")[0];
19             var btnClass = document.getElementsByClassName("btn");        
20         button.onclick = function(){
21             var deleteButton = document.createElement("button");    
22             var value = text.value;
23                 deleteButton.setAttribute("class","btn");
24             var deleteText = document.createTextNode("删除");
25                 deleteButton.appendChild(deleteText);
26             var li = document.createElement("li");
27             var liText = document.createTextNode(value);
28                 li.appendChild(liText);
29                 li.appendChild(deleteButton);
30                 ul.appendChild(li);
31             for(var i=0;i<btnClass.length;i++){
32                 btnClass[i].onclick=function(){
33                 this.parentNode.parentNode.removeChild(this.parentNode);
34             }
35         }
36         }
37 
38             for(var i=0;i<btnClass.length;i++){
39                 btnClass[i].onclick=function(){
40                     this.parentNode.parentNode.removeChild(this.parentNode);
41                 }
42             }
43     </script>
44 </body>
45 </html>

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10.Generator抽奖逻辑

 1 <script type="text/javascript"> 
 2 /*generator实现抽奖逻辑*/
 3     let draw=function(count){
 4         console.info(`剩余${count}`);
 5     }
 6     let residue=function* (count){
 7         while(count>0){
 8             count--;
 9             yield draw(count);
10         }
11     }
12 
13     let star=residue(5);  //将Generator实例
14     star.next()
15     star.next()
16     star.next()
17 </script>

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11.检测数据类型

//写出一个比typeof运算符更准确的类型判断函数。

var type = function (o){
  var s = Object.prototype.toString.call(o);
  return s.match(/\[object (.*?)\]/)[1].toLowerCase();
};

type({}); // "object"
type([]); // "array"
type(5); // "number"
type(null); // "null"
type(); // "undefined"
type(/abcd/); // "regex"
type(new Date()); // "date"

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    function checkedType(target){
        return Object.prototype.toString.call(target).slice(8,-1);
    }

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    <script>
        let str=1234;
        let str3=str.constructor.toString();  //返回：function Number() { [native code] }
        alert(str3.slice(9,-20))
    </script>

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12.数组去重——Array.filter()

let arr=[2,3,4,2,3];
console.log(arr.filter(function(item,index,self){
    return self.indexOf(item)==index}
    )
)

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注:性能差javascript

13.数组/字符串去重——利用for循环去重

/*var arr1 ="abcdabcd";*/
var arr1=['a','b','c','a','d','b']
var arr2=[];
for(var i=0;i<arr1.length;i++){
    if(arr2.indexOf(arr1[i])<0){
　　　　　　arr2.push(arr1[i]);
       }
 }
document.write(arr2);

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注:性能良好php

13.1数组去重——ES6（Set）

let arr=[1,2,3,4,5,3,5,6,2];
let a=new Set(arr);
let b=[...a];
console.log(b);//[1,2,3,4,5,6]

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注:性能优css

13.2数组去重——建立空对象

 1 let arr=[1,2,3,4,5,3,5,6,2];
 2 let b=[];
 3 let c={};
 4 for(let i=0;i<arr.length;i++){
 5    if(!c[arr[i]]){
 6        b.push(arr[i]);
 7        c[arr[i]]='hello';   //
 8    }
 9 }
10 console.log(b);//[ 1, 2, 3, 4, 5, 6 ]
11 console.log(c);
12 /*{1: "hello", 2: "hello", 3: "hello", 4: "hello", 5: "hello", 6: "hello"}*/

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注:性能最优html

13.3数组去重——利用splice

function newArr(arr){
    for(var i=0;i<arr.length;i++){
        for(var j=i+1;j<arr.length;j++)
            if(arr[i]==arr[j]){ 
            //若是第一个等于第二个，splice方法删除第二个
            arr.splice(j,1);
            j--;
            }
        }
 
    return arr;
 }
var arr = [1,1,2,5,6,3,5,5,6,8,9,8];
 
console.log(newArr(arr))

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注：性能最差vue

13.4数组去重——利用filter

[1,2,3,1,'a',1,'a'].filter(function(ele,index,array){
    return index===array.indexOf(ele)
})

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13.4数组去重——Array.sort()

function distinct(a, b) {
    let arr = a.concat(b)
    arr = arr.sort()
    let result = [arr[0]]

    for (let i=1, len=arr.length; i<len; i++) {
        arr[i] !== arr[i-1] && result.push(arr[i])
    }
    return result;
}
console.log(distinct([4,3,2],[5,4,2])) //[2,3,4,5]

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13.5字符串去重——ES6(set)

[...new Set('ababbc')].join('')
// "abc"

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14.1判断数组是否存在重复值

var arr=['333','222','222','444','333'];
var s=arr.join(",")+",";
for(var i=0;i<arr.length;i++){
     if(s.replace(arr[i]+",","").indexOf(arr[i]+",")>0)
           alert("数组中有重复元素：" + arr[i]);
}

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14.2判断数组是否存在重复值（2）

var ary = new Array("111","22","33","111");
var nary=ary.sort();

for(var i=0;i<ary.length;i++){
       if (nary[i]==nary[i+1]){
             alert("数组重复内容："+nary[i]);
       }
}

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14.3判断数组是否存在重复值（3）

function isRepeat(arr){
    var hash = [];
    for(var i in arr) {
         if(hash[arr[i]])
            return true;
         hash[arr[i]] = true;
}
     return false;
}

var arr=["111","22","33","111"];
alert(isRepeat(arr))

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15.获取浏览URL中查询字符串的参数

 1 function showWindowHref(arr){
 2     var sHref = arr;
 3     var args = sHref.split('?');
 4     if(args[0] == sHref){
 5         return "";
 6     }
 7     var arr = args[1].split('&');
 8     alert(arr)    //staffid=12333,name=xiaoming,age=23
 9     var obj = {};
10     for(var i = 0;i< arr.length;i++){
11         var arg = arr[i].split('=');
12         obj[arg[0]] = arg[1];
13         console.log(obj[arg[0]])    //12333,xiaomi,23
14     }
15     return obj;
16 }
17 var href = showWindowHref("https://www.runoob.com/jsref/met-win-close.html?staffid=12333&name=xiaoming&age=23"); // obj
18 alert(href['name']); // xiaoming

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16.原生Ajax

 1 <!DOCTYPE html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>原生的Ajax</title>
 6 </head>
 7 <body>
 8 <h1></h1>
 9 <script>
10     var xmlhttp;
11     load();
12     function load(){
13         if(window.XMLHttpRequest){
14             xmlhttp=new XMLHttpRequest();
15             //  IE7+, Firefox, Chrome, Opera, Safari 浏览器执行代码
16         }else {
17             xmlhttp=new ActiveXObject('Microsoft.XMLHTTP');
18             //IE6 5
19         }
20         xmlhttp.onreadystatechange=function(){
21             if(xmlhttp.readyState===4&&xmlhttp.status===200){
22 //                0: 请求未初始化
23 //                1: 服务器链接已创建
24 //                2: 请求已接收
25 //                3: 请求处理中
26 //                4: 请求已完成，且响应已就绪
27 //                200: "OK"
28 //                404: 未找到页面
29                 //responseText表明字符串形式回应  responseXML表明XML形式回应
30                 document.getElementsByTagName('h1')[0].innerHTML=xmlhttp.responseText;
31             }
32         };
33         xmlhttp.open('GET','http://www.wangwei123.cn/xx/public/admin/aside/typelist',true);//TRUE表明异步
34         xmlhttp.send();
35     }
36 </script>
37 </body>
38 </html>

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 1 100——客户必须继续发出请求
 2 101——客户要求服务器根据请求转换HTTP协议版本
 3 200——交易成功
 4 201——提示知道新文件的URL
 5 202——接受和处理、但处理未完成
 6 203——返回信息不肯定或不完整
 7 204——请求收到，但返回信息为空
 8 205——服务器完成了请求，用户代理必须复位当前已经浏览过的文件
 9 206——服务器已经完成了部分用户的GET请求
10 300——请求的资源可在多处获得
11 301——删除请求数据
12 302——在其余地址发现了请求数据
13 303——建议客户访问其余URL或访问方式
14 304——客户端已经执行了GET，但文件未变化
15 305——请求的资源必须从服务器指定的地址获得
16 306——前一版本HTTP中使用的代码，现行版本中再也不使用
17 307——申明请求的资源临时性删除
18 400——错误请求，如语法错误
19 401——请求受权失败
20 402——保留有效ChargeTo头响应
21 403——请求不容许
22 404——没有发现文件、查询或URl
23 405——用户在Request-Line字段定义的方法不容许
24 406——根据用户发送的Accept拖，请求资源不可访问
25 407——相似401，用户必须首先在代理服务器上获得受权
26 408——客户端没有在用户指定的时间内完成请求
27 409——对当前资源状态，请求不能完成
28 410——服务器上再也不有此资源且无进一步的参考地址
29 411——服务器拒绝用户定义的Content-Length属性请求
30 412——一个或多个请求头字段在当前请求中错误
31 413——请求的资源大于服务器容许的大小
32 414——请求的资源URL长于服务器容许的长度
33 415——请求资源不支持请求项目格式
34 416——请求中包含Range请求头字段，在当前请求资源范围内没有range指示值，请求也不包含If-Range请求头字段
35 417——服务器不知足请求Expect头字段指定的指望值，若是是代理服务器，多是下一级服务器不能知足请求
36 500——服务器产生内部错误
37 501——服务器不支持请求的函数
38 502——服务器暂时不可用，有时是为了防止发生系统过载
39 503——服务器过载或暂停维修
40 504——关口过载，服务器使用另外一个关口或服务来响应用户，等待时间设定值较长
41 505——服务器不支持或拒绝支请求头中指定的HTTP版本

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17.短横线转换为驼峰命名

 1         <script type="text/javascript">
 2             window.onload = function() {
 3                 new Camel('border-bottom-color');
 4             }
 5 
 6             function Camel(str) {
 7                 this.result = '';
 8                 this.arr = str.split('-');
 9                 this.result += this.arr[0].toString();
10                 for(var i = 1; i < this.arr.length; i++) {
11                     var str1 = this.arr[i].toString();
12                     var str2 = str1.charAt(0).toUpperCase();
13                     var str3 = str2 + str1.slice(1);
14                     this.result += str3;
15                 }
16                 console.log(this.result);  //borderBottomColor
17             }
18         </script>

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18.vue实现简单购物车

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8" />
        <title>vue综合练习</title>
        <style type="text/css">
            td{
                align-content: center;
            }
        </style>
    </head>
    <body>
        <div id="app">
            <h3>购物车</h3>
            <h4 v-if="products.length==0">空空如也</h4>
            <div v-else>
                <table border="1" cellspacing="0" align="center">
                    <tr>
                        <th>编号</th>
                        <th>商品名称</th>
                        <th>商品价格</th>
                        <th>商品数量</th>
                        <th>操做</th>
                    </tr>
                    <tr v-for="(product,index) in products">
                        <td>{{index+1}}</td>
                        <td>{{product.name}}</td>
                        <td>{{product.price}}</td>
                        <td><button @click="reduce(index)">-</button>{{product.num}}<button @click="add(index)">+</button></td>
                        <td><button @click="del(index)">删除</button></td>
                    </tr
                    <tr>
                        <td colspan="5">总价：{{total}}</td>
                    </tr>
                </table>
            </div>
        </div>
        <script type="text/javascript" src="vue.js" ></script>
        <script>
            var app = new Vue({
                el: "#app",
                data: {
                    products:[
                        {id:1,name:"西瓜",price:20.00,num:4},
                        {id:2,name:"牛奶",price:30.00,num:2},
                        {id:3,name:"榴莲",price:80.00,num:1}
                    ],
                    total:0
                },
                methods:{
                    //新版本写法：del(){}
                    //删除商品
                    del (index) {
                        this.products.splice(index,1);
                        this.count();
                    },
                    //减小数量
                    reduce (index) {
                        if(this.products[index].num>0){
                        this.products[index].num--;
                        this.count();
                    }
                    },
                    //增长商品数量
                    add (index){
                        this.products[index].num++;
                        this.count();
                    },
                    //计算商品总价
                    count () {
                        this.total=0;
                        for(var i in this.products){
                            this.total+=this.products[i].price*this.products[i].num;
                        }

                    }
                },
                //最后运行
                mounted(){
                    this.count();
                }
            });

        </script>
    </body>
</html>

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18.2.vue实现简单购物车2

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
    *{margin:0;padding: 0;}
    .checkout-title {
        position: relative;
        margin-bottom: 41px;
        text-align: center; 
    }
  .checkout-title span {
        position: relative;
        padding: 0 1em;
        background-color: #fff;
        font-family: "moderat", sans-serif;
        font-weight: bold;
        font-size: 20px;
        color: #605F5F;
        z-index: 1; 
    }
    .checkout-title:before{
        position: absolute;
        content: '';
        border-bottom: 1px solid green;
        width: 100%;
        top:50%;
        left: 0;
        z-index: 0;
    }
/*  居中线制做方法2
    .checkout-title:before {
        position: absolute; /*相对定位取决于checkout-title的position:relative
        content: "";
        height: 1px;    //修改高度便可
        width: 100%;
        top: 50%;
        left: 0;
        background: #ccc;
        z-index: 0; 
    }
    */
    </style>
</head>
<body>
        <div class="checkout-title">
             <span>购物车</span>
        </div>
</body>
</html>

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19.vue——卡片列表循环单击选中效果

<li v-for="(item,index) in filterAddress"  v-bind:class="{'check': index == currentIndex}" @click="currentIndex=index"> 
 /*filterAddress计算属性的方法值能够放在，充当数组*/
//@click="currentIndex=index"标明了将点击的索引值赋给currentIndex，index == currentIndex自身的索引和当前点击事件索引相同，则产生选中事件
/*当产生点击事件后，第一个currentIndex由于相等因此产生true，check类就能够渲染，v:bind和@click结合使用，会产生奇妙的状态！*/

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<li v-for="(item,index) in filterAddress"  v-bind:class="{'check': index == current && current !== ' '}" @click="current=index"> 
 /*current默认为空,而后默认不会被选中*/

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注:与1的手风琴效果相似java

20.深度拷贝

var deepCopy = function(obj) {
    if (typeof obj !== 'object') return;
    var newObj = obj instanceof Array ? [] : {};
    for (var key in obj) {
        if (obj.hasOwnProperty(key)) {
            newObj[key] = typeof obj[key] === 'object' ? deepCopy(obj[key]) : obj[key];
        }
    }
    return newObj;
}

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<script type="text/javascript">
    /*
        思考:
            如何实现深度拷贝(克隆)
            拷贝的数据里有对象/数组
            拷贝的数据里不能有对象/数组,即便有对象/数组能够继续遍历对象、数组拿到里边每一项值，一直拿到是基本数据类型，而后再去复制，就是深度拷贝。
    */

    //知识点储备
    /*
        如何判断数据类型:arr-Array null -Null
        1.typeof返回的数据类型有:String，Number,Boolean,Undefined,Object,Function。
        2.Object.prototype.toString.call(obj)。
    */
    
    let result = 'abcd';
    result = null;
    result = [1,3];
    console.log(Object.prototype.toString.call(result).slice(8,-1)); //[object Array]，sclice截取字符串后:Array(拿到分类)。
    //console.log(typeof Object.prototype.toString.call(result));  //string


    //for in 循环对象(属性名)、数组(下标)，推荐在循环对象属性的时候，使用for...in,在遍历数组的时候的时候使用for...of。
    //for in 循环遍历对象属性名
    let obj = {username:'zhangsan',age:22};
    for(let i in obj){
        console.log(i);  //username age
    }

    //for in 循环遍历数组下标
    let arr = [1,3,'abc'];
    for(let i in arr){        //数组的能够用for of对应数组值
        console.log(i); //0 1 2
    }

    //定义检测数据类型的功能函数
    function checkedType(target){
        return Object.prototype.toString.call(target).slice(8,-1);
    }
    console.log(checkedType(result));  //Array

    //实现深度克隆--对象/数组
    function clone(target){
        //判断拷贝的数据类型
        //初始化变量的result 成为最终克隆的数据
        let result,targetType = checkedType(target);
        if(targetType === 'Object'){
            result = {};
        }else if(targetType === 'Array'){
            result = [];
        }else{
            return target;   //若是是基本数据类型:(String, Number, boolean, Null, Undefined)就直接反回去。
        }

        //遍历目标数据
        for(let i in target){
           //获取遍历数据结构的每一项值。
            let value = target[i];   //i=1,i=2,i=..
              //判断目标结构里的每一值是否存在对象/数组
            if(checkedType(value) === 'Object' || checkedType(value) === 'Array'){ //若是对象OR数组里嵌套了对象/数组
                //继续遍历获取到的value值
                result[i] = clone(value);    //这个只执行一次,数组里只有一个对象
            }else{  //获取到的value值是基本的数据类型或者是函数。
                result[i] = value;  //由于arr3数组的下标0和1都是Number类型,只有下标2才是Object(转去执行1046行)
            }
        }
        return result;
    }
    let arr3 = [1,2,{username:'dudu',age:32}];
    let arr4 = clone(arr3);    //至关于复制了一份arr3的基本数据
    console.log(arr4);
    arr4[2].username = 'gate';
    arr4[2].age = 65;
    console.log(arr3,arr4);  //arr3下标2是{username:'dudu':age:32},arr4下标2是{username:gate,age:65}
</script>

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21.ES6——Primise-async语法实现红绿灯

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>实现一个红绿灯</title>
    <style>
        #traffic-light {
            width: 50px;
            height: 50px;
            border-radius: 50%;
            border: 1px solid #000; 
        }
        .traffic-box {
            display: flex;
            flex-direction: column;
        }
        .traffic {
            width: 50px;
            height: 50px;
            margin: 5px 0;
            border-radius: 50%;
            border: 1px solid #000; 
        }
        .red { background-color: red;}
        .yellow { background-color: yellow;}
        .green { background-color: green;}
    </style>
</head>
<body>
    <header>
        <h1>实现一个红绿灯，把一个圆形 div 按照绿色 3 秒，黄色 1 秒，红色 2 秒循环改变背景色</h1>
        <p>Promise、async\await 语法实现</p>
    </header>
    <div id="traffic-light"></div>
    <hr/>
    <div class="traffic-box">
        <div id="traffic-red" class="traffic"></div>
        <div id="traffic-yellow" class="traffic"></div>
        <div id="traffic-green" class="traffic"></div>
    </div>
    <script>
        function sleep(duration) {
            return new Promise(function(reslove){
                setTimeout(reslove, duration);
            })
        }

        async function changeColor(duration, color) {
            document.getElementById("traffic-light").style.background = color;
            await sleep(duration);
        }

        async function main(){
            while(true){
                await changeColor(3000,"green");
                await changeColor(1000, "yellow");
                await changeColor(2000, "red");
            }
        }
        main()

        //***************************************************************
        var red = document.getElementById('traffic-red')
        var yellow = document.getElementById('traffic-yellow')
        var green = document.getElementById('traffic-green')
        async function changeColor2(duration, color) {
            console.log(duration, color)
            if (color === 'red') {
                red.classList.add('red');
                yellow.classList.remove('yellow')
                green.classList.remove('green')
            } else if (color === 'yellow') { 
                yellow.classList.add('yellow');
                red.classList.remove('red')
                green.classList.remove('green')
            } else {
                green.classList.add('green');
                red.classList.remove('red')
                yellow.classList.remove('yellow')
            } 
            await sleep(duration);
        }
        async function main2(){
            while(true){
                await changeColor2(3000,"green");
                await changeColor2(1000, "yellow");
                await changeColor2(2000, "red");
            }
        }
        main2()
    </script>
</body>
</html>

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22.HTML5拖拽图片上传及本地预览

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>HTML5拖拽上传</title>
    <style>
        .upload-arae { 
            min-width: 300px; 
            min-height: 150px; 
            border: 1px dashed #ccc; 
            border-radius:3px; 
            display: flex;
            justify-content: center;
            align-items: center;
            color: #ccc;
            margin-bottom: 10px;
        }
        .tip {
            text-align: center;
        }
        .dragover {
            border: 1px dashed blue; 
        }
        .button {
            color: #fff;
            background-color: #20a0ff;
            border-color: #20a0ff;
            border-radius: 4px;
            font-size: 14px;
            padding: 5px 15px;
            cursor: pointer;
        }
    </style>
</head>
<body>
    <h1>HTML5拖拽上传及本地预览</h1>
    <div id="rate" class="upload-arae">
        <div class="tip">
            <p>将文件拖拽到此处开始上传！</p>
            <label for="inputFile" class="button">选择文件</label>
            <input type="file" name="file" id="inputFile" onchange="changeUpload(event)" style="display:none">
        </div>
    </div>
    <div id="viewImg">
    </div>
</body>
<script>   //只能实现拖拽图片
    var rate = document.getElementById('rate');
    var viewImg = document.getElementById('viewImg');
    document.addEventListener('dragenter', function (e) {
        e.stopPropagation();
        e.preventDefault();
        rate.classList.add('dragover')
    }, false)
    document.addEventListener('dragover', function (e) {
        e.stopPropagation();
        e.preventDefault();
    }, false);
    document.addEventListener('drop', function (e) {
        e.stopPropagation();
        e.preventDefault();
        sendFile(e || window.event);
        rate.classList.remove('dragover')
    }, false);
    function sendFile(e) {
        var files = e.dataTransfer.files;
        console.log('files', files)
        if (!files || files.length < 1) {
            return;
        }
        toViewImg(files[0])
    }
    function changeUpload(ev) {
        let files = ev.target.files;
        toViewImg(files[0])
    }
    function toViewImg(file) {
        var reader = new FileReader();
        reader.readAsDataURL(file)
        reader.onload = function (e) {
            viewImg.innerHTML = '上传中...'
            var img = this.result
            setTimeout(function(){
                viewImg.innerHTML = '<img src="' + img + '" />'
            }, 2000)
        }
    }
</script>
</html>

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23.使用js实现极简Vue.js双向数据绑定功能

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>实现极简Vue.js双向数据绑定</title>
</head>
<body>

<div id="app">
    <input type="text" v-model="message">
    {{message}}
</div>

<script>
    function observer(obj, vm) {
        Object.keys(obj).forEach(function(key){
            defineReactive(vm, key, obj[key]);
        });
    }

    function defineReactive(obj, key, val) {
        var dep = new Dep();
        Object.defineProperty(obj, key, {
            get: function() {
                console.log('Dep.target', Dep.target);
                if(Dep.target) dep.addSub(Dep.target);
                return val;
            },
            set: function(newVal) { //检测更新的时候，会自动调用并传入新值
                if(newVal === val) return; //没有更新，直接返回
                val = newVal;
                dep.notify(); //发出通知
            }
        });
    }

    function Dep() {
        this.subs = [];
    }
    Dep.prototype = {
        addSub: function(sub) {
            this.subs.push(sub);
        },
        notify: function() {
            this.subs.forEach(function(sub) {
                sub.update();//更新
            });
        }
    };

    function nodeToFrangment(node, vm) { //node:ID元素
        //渲染个数不肯定
        var flag = document.createDocumentFragment();
        var child;
        while(child = node.firstChild) {//逐个渲染
            compile(child, vm)//解析操做
            flag.append(child);
        }
        return flag;
    }

    function compile(node, vm) {
        var reg = /\{\{(.*)\}\}/;   //正则匹配{{}}
        var textType = 'input';
        if(node.nodeType === 1) { //v-model
            var attrs = node.attributes;
            for (var i = 0; i < attrs.length; i++) {
                if(attrs[i].nodeName === 'v-model') {
                    var name = attrs[i].nodeValue;
                    node.addEventListener('input', function(e){
                        vm[name] = e.target.value;//对数据更新，调用set方法
                    });
                    node.value = vm[name];
                    node.removeAttribute('v-model');
                }
            }
        }
        if(node.nodeType === 3) {   //text
            if(reg.test(node.nodeValue)) {
                var name = RegExp.$1;
                name = name.trim();
                textType = 'text';
            }
        }
        new Watcher(vm, node, name, textType);
    }

    function Watcher(vm, node, name, nodeType) {
        Dep.target = this;
        this.name = name;
        this.vm = vm;
        this.node = node;
        this.nodeType = nodeType;
        this.update();
        Dep.target = null;
    }

    Watcher.prototype = {
        update: function() {
            this.get();
            if(this.nodeType === 'text') {
                this.node.nodeValue = this.value;
            }
            if(this.nodeType === 'input') {
                this.node.value = this.value;
            }
        },
        get: function() {//获取data中的属性值
            this.value = this.vm[this.name];
        }
    };

    function Vue(opt) { //更新数据  解析指令
        this.data = opt.data;
        var data = this.data;
        observer(data, this); //监听数据
        var id = opt.el;

        var dom = nodeToFrangment(document.getElementById(id), this);
        document.getElementById(id).appendChild(dom);
    }

    var v = new Vue({
        el: 'app',
        data: {
            message: 'hello lucas'
        }
    });
</script>    
</body>
</html>

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<--! HTML代码-->
<body>
    <p>
        input1=><input type="text" id="input1">
    </p>
    <p>
        input2=>
        <input type="text" id="input2">
    </p>
    <div>
        我每次比input1的值加1=>
        <span id="span"></span>
    </div>
</body>

<--! JS代码-->

var oInput1 = document.getElementById('input1');
var oInput2 = document.getElementById('input2');
var oSpan = document.getElementById('span');
var obj = {};
Object.defineProperties(obj, {
    val1: {
        configurable: true,
        get: function() {
            oInput1.value = 0;
            oInput2.value = 0;
            oSpan.innerHTML = 0;
            return 0
        },
        set: function(newValue) {
            oInput2.value = newValue;
            oSpan.innerHTML = Number(newValue) ? Number(newValue) : 0
        }
    },
    val2: {
        configurable: true,
        get: function() {
            oInput1.value = 0;
            oInput2.value = 0;
            oSpan.innerHTML = 0;
            return 0
        },
        set: function(newValue) {
            oInput1.value = newValue;
            oSpan.innerHTML = Number(newValue)+1;
        }
    }
})
oInput1.value = obj.val1;
oInput1.addEventListener('keyup', function() {
    obj.val1 = oInput1.value;
}, false)
oInput2.addEventListener('keyup', function() {
    obj.val2 = oInput2.value;
}, false)

View Code

24.左中右三栏布局，中间自适应，5种布局方法

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>左中右三栏布局，中间自适应，5种布局方法</title>
    <style>
        body{
            margin: 0;
            padding: 0;
        } 
        /**  FlexBox  **/
        .container{display: flex;}
        .container div{min-height: 100px;}
        .container .left,
        .container .right{width: 300px; background-color: orange;}
        .container .center{flex:1;background-color: #ccc;}

        /**  Float  **/
        .container2 div{min-height: 100px;}
        .container2 .left,
        .container2 .right{background-color: palegreen;width: 300px;}
        .container2 .center{background-color: #ccc}
        .container2 .left{float: left;}
        .container2 .right{float: right;}

        /**  absolute  **/
        .container3{min-height: 100px;}
        .container3 div{min-height: 100px;position: absolute;}
        .container3 .left,
        .container3 .right{background-color: palegreen;width: 300px;}
        .container3 .center{background-color: #ccc;left: 300px;right: 300px;}
        .container3 .left{left: 0;}
        .container3 .right{right: 0;}

        /**  table  **/
        .container4{width: 100%;height: 100px;display: table;}
        .container4 div{display: table-cell;}
        .container4 .left,
        .container4 .right{background-color: palegreen;width: 300px;}
        .container4 .center{background-color: #ccc;}

        /**  CSS Grid  **/
        .container5{
            width: 100%;
            display: grid;
            grid-template-rows: 100px;
            grid-template-columns: 300px auto 300px;
        }
        .container5 div{min-height: 100px;}
        .container5 .left,
        .container5 .right{background-color: palegreen;}
        .container5 .center{background-color: #ccc;}

        /**  双飞翼（浮动）  **/
        .container6{
            
        }
        .container6 div{min-height: 100px;}
        .container6 .left,
        .container6 .right{background-color: palegreen;}
        .container6 .center{background-color: #ccc;}
    </style>
</head>
<body>
    
    <!-- 假设高度已知，左右宽度各位三百，中间自适应 -->
    <h1>左中右三栏布局，中间自适应</h1>
    <h2>1. FlexBox方案</h2>
    <div class="container">
        <div class="left"></div>
        <div class="center">
            左中右三栏布局，中间自适应，FlexBox方案左中右三栏布局，中间自适应，FlexBox方案左中右三栏布局，
            中间自适应，FlexBox方案左中右三栏布局，中间自适应，FlexBox方案左中右三栏布局，中间自适应，FlexBox方案
        </div>
        <div class="right"></div>
    </div>

    <h2>2. Float方案</h2>
    <div class="container2">
        <div class="left"></div>
        <div class="right"></div>
        <div class="center">
            左中右三栏布局，中间自适应，Float方案左中右三栏布局，中间自适应，Float方案左中右三栏布局，中间自适应，
            Float方案左中右三栏布局，中间自适应，Float方案左中右三栏布局，中间自适应，Float方案左中右三栏布局，中间自适应
        </div>
    </div>

    <h2>3. 绝对定位方案</h2>
    <div class="container3">
        <div class="left"></div>
        <div class="center">
            左中右三栏布局，中间自适应，绝对定位方案左中右三栏布局，中间自适应，绝对定位方案左中右三栏布局，
            中间自适应，绝对定位方案左中右三栏布局，中间自适应，绝对定位方案左中右三栏布局，中间自适应，绝对定位方案
        </div>
        <div class="right"></div>
    </div>

    <h2>4. 格布局方案</h2>
    <div class="container4">
        <div class="left"></div>
        <div class="center">
            左中右三栏布局，中间自适应，表格布局方左中右三栏布局，中间自适应，表格布局方左中右三栏布局，中间自适应
            左中右三栏布局，中间自适应，表格布局方左中右三栏布局，中间自适应，表格布局方左中右三栏布局，中间自适应，
        </div>
        <div class="right"></div>
    </div>

    <h2>5. 网格布局方案</h2>
    <div class="container5">
        <div class="left"></div>
        <div class="center">
            左中右三栏布局，中间自适应，网格布局方案左中右三栏布局，中间自适应，网格布局方案左中右三栏布局，中间自适应，网格布局方案
            左中右三栏布局，中间自适应，网格布局方案左中右三栏布局，中间自适应，网格布局方案左中右三栏布局，中间自适应，网格布局方案
        </div>
        <div class="right"></div>
    </div>

    <h2>6. 双飞翼（浮动）布局方案</h2>
    <div class="container6">
        <div class="main">
            <div class="center">
            双飞翼（浮动）布局方案双飞翼（浮动）布局方案双飞翼（浮动）布局方案双飞翼（浮动）布局方案双飞翼（浮动）布局方案
            双飞翼（浮动）布局方案双飞翼（浮动）布局方案双飞翼（浮动）布局方案双飞翼（浮动）布局方案双飞翼（浮动）布局方案
        </div>
        </div>
        <div class="left"></div>
        <div class="right"></div>
    </div>
</body>
</html>

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25.DIV模板引擎

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>DIV模板引擎</title>
</head>

<body>
    <h1>DIV模板引擎</h1>
    <script>
        var Template = function (tempstr, data) {
            var re = /<%([^%>]+)?%>/g,
                cursor = 0, // 字符串的查找位置
                reExp = /^\s*(for|if|else|switch|case|break|continue|{|})(.*)?/g,
                code = 'var arr = [];\n';   
            var add = function (line, flag) { //flag --> 判断是不是JS代码
                // 第一次：line ==> 个人名字是：
                code += flag ? line.match(reExp) ? line : 'arr.push(' + line + ');\n'
                    : 'arr.push("' + line.replace(/"/, '\\"') + '");\n';
            }
            while (item = re.exec(tempstr)) {
                add(tempstr.slice(cursor, item.index));
                add(item[1], true);
                cursor = item.index + item[0].length;
            }
            add(tempstr.substring(cursor));
            code += 'return arr.join("");';
            return new Function(code.replace(/[\r\n\t]/g, '')).apply(data);
        }
        
        // var str = '个人名字是：<%this.name%>，年龄是：<%this.profile.age%>，Over！！！';
        // var res = Template(str, {
        //   name: 'Dunizb',
        //   profile: {
        //     age: 22
        //   }
        // });
        // console.log(res);
        
        var str = '个人爱好：<%for(var i in this.hobby){%>'
            + '<p><%this.hobby[i]%></p>'
            + '<%}%>';
        var res = Template(str, {
            hobby: ['php', 'java', 'javascript', 'linux', 'python']
        });
        document.write(res);
    </script>
</body>

</html>

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26.省市两级级联下拉列表

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>省市两级级联下拉列表</title>
</head>
<body>
    <select id="province">
        <option>==请选择省份==</option>
    </select>
    <select id="city">
        <option>==请选择城市==</option>
    </select>
</body>
<script>
    // 准备数据
    var data = [
        {"code" : "0001", "name" : "广东省",
            "cities" : [
                {"code" : "00010001", "name" : "广州市"},
                {"code" : "00010002", "name" : "深圳市"},
                {"code" : "00010003", "name" : "东莞市"}
            ]
        },
        {"code" : "0002", "name" : "湖南省",
            "cities" : [
                {"code" : "00020001", "name" : "长沙市"},
                {"code" : "00020002", "name" : "衡阳市"},
                {"code" : "00020003", "name" : "郴州市"}
            ]
        },
        {"code" : "0003", "name" : "江西省",
            "cities" : [
                {"code" : "00030001", "name" : "南昌市"},
                {"code" : "00030002", "name" : "赣州市"},
                {"code" : "00030003", "name" : "吉安市"}
            ]
        }
    ];

    window.onload = function(){
        // 获取省份城市select
        var proSelect = document.getElementById("province");
        for (var i = 0; i < data.length; i++){
            var json = data[i];
            var option = new Option(json.name, json.code, false, false);
            proSelect.add(option);
        }
        // 为proSelect绑定onChange事件
        proSelect.onchange = function(){
            var citySelect = document.getElementById("city");
            // 在下次选择省份以前先清空城市下拉列表
            for (var i = citySelect.length - 1; i > 0; i--){
                citySelect.remove(i);
            }
            for (var i = 0; i < data.length; i++){
                var json = data[i];
                if (json.code == this.value){
                    // 取城市
                    var cities = json.cities;
                    for (var j = 0; j < cities.length; j++){
                        // 获取其中的json
                        var temp = cities[j];
                        var option = new Option(temp.name, temp.code, false, false);
                        citySelect.add(option);
                    }
                }   
            }
        }
    }
</script>
</html>

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27.CSS3——打字延迟动画

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title>打字动画</title>
    <style>
        body {background-color: #000;color:green;}
        p {
            width: 27em;      /*这里控制打字的宽度和子长,也能够取消下面的JS注释 */
            font-family: Menlo, Monaco, Consolas, "Courier New", monospace;
            overflow: hidden;
            white-space: nowrap;
            border-right: .05em solid transparent;/*兼容处理*/
            border-right: .05em solid;
            animation: typing 6s steps(16),   
                       caret 1s steps(1) infinite;
        }
        @keyframes typing {
            from { width: 0; }
        }
        @keyframes caret {
            50% { border-right-color: transparent; }
        }
    </style>
</head>
<body>
<p>Javascript是世界最好的语言,hello world,hello lucas！</p>
    <script>
        /*** 此段JS代码的目的是为了动态设置文字的宽度和步长 ****/

       // var ps = document.getElementsByTagName("p");
       // for(var i=0 ;i<ps.length; i++){
       //     var len = ps[i].textContent.length;
       //     ps[i].style.width = len + 'em';
       //     ps[i].style.animationTimingFunction = "steps("+len+"),steps(1)";
       // }
    </script>
</body>
</html>

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28.CSS3——文字闪烁动画

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title>文字闪烁</title>
    <style>
        .hightlight {
            width: 500px;
            margin: 100px auto;
            font:700 20px/20px "Microsoft YaHei";
            animation: 1s blink 3 steps(1) ;
        }
        @keyframes blink {
            50% { color: transparent; }
        }
    </style>
</head>
<body>
<div class="hightlight">hello lucas</div>
</body>
</html>

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29.数组与字符串对象相同的方法

concat()
indexOf()
lastIndexOf()
includes()
toString()
slice()

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30.找出数组最大个数

//es5写法
function maxNumber(){
    var arr = [10,29,5]
    document.write(Math.max.apply(null,arr))
}

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//es6拓展运算符...

Math.max(...arr)

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arr.sort((num1, num2) => {
    return num1 - num2 < 0
})
arr[0]

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let max = arr[0];
for (let i = 0; i < arr.length - 1; i++) {
    max = max < arr[i+1] ? arr[i+1] : max
}

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31.JS简单数组排序

function sortNumber(a,b)
{
    return a - b;  //若是须要降序排序能够把a与b调换便可
}

var arr = new Array(6)
arr[0] = "10"
arr[1] = "5"
arr[2] = "40"
arr[3] = "25"
arr[4] = "1000"
arr[5] = "1"

document.write(arr + "<br />")
document.write(arr.sort(sortNumber))

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    var arr = [1, 7, 10, 4, 6];
    function compare(val1, val2) {
      if(val1 < val2) {
        return -1;
      } else if(val1 > val2) {
        return 1;
      } else {
        return 0;
      }
    };
    arr.sort(compare);
    console.log(arr);

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32.对数组进行随机排序

var points = [40, 100, 1, 5, 25, 10];
document.getElementById("demo").innerHTML = points;  

function myFunction() {
  points.sort(function(a, b){return 0.5 - Math.random()});
  document.getElementById("demo").innerHTML = points;
}

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33.为不具有 Iterator 接口的对象提供遍历方法

function* objectEntries(obj) {
    const propKeys = Reflect.ownKeys(obj);
    for (const propKey of propKeys) {
        yield [propKey, obj[propKey]];
    }
}
 
const jane = { first: 'Jane', last: 'Doe' };
for (const [key,value] of objectEntries(jane)) {
    console.log(`${key}: ${value}`);
}
// first: Jane
// last: Doe

//Reflect.ownKeys() 返回对象全部的属性，无论属性是否可枚举，包括 Symbol。

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34.嵌套数组的平铺

function* iterTree(tree) {
  if (Array.isArray(tree)) {
    for(let i=0; i < tree.length; i++) {
      yield* iterTree(tree[i]);
    }
  } else {
    yield tree;
  }
}

const tree = [ 'a', ['b', 'c'], ['d', 'e'] ];

for(let x of iterTree(tree)) {
  console.log(x);
}
// a
// b
// c
// d
// e

//因为扩展运算符...默认调用 Iterator 接口，因此上面这个函数也能够用于嵌套数组的平铺。

`[...iterTree(tree)] // ["a", "b", "c", "d", "e"]`

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35.Markdown源码

  1 <!DOCTYPE html>
  2 <html lang="en">
  3 
  4 <head>
  5     <meta charset="UTF-8">
  6     <title>md转换为html</title>
  7     <script src="https://cdnjs.cloudflare.com/ajax/libs/showdown/1.9.0/showdown.min.js"></script>
  8 </head>
  9 
 10 <body>
 11     <div style="font-size: 20px;height: 30px; text-align: center;color: #009689; font-weight: bold;">Markdown转换为HTML的Demo</div>
 12     <style>
 13     .markdown-here-wrapper {
 14         font-size: 16px;
 15         line-height: 1.8em;
 16         letter-spacing: 0.1em;
 17     }
 18 
 19     pre,
 20     code {
 21         font-size: 14px;
 22         font-family: Roboto, 'Courier New', Consolas, Inconsolata, Courier, monospace;
 23         margin: auto 5px;
 24     }
 25 
 26     code {
 27         white-space: pre-wrap;
 28         border-radius: 2px;
 29         display: inline;
 30     }
 31 
 32     pre {
 33         font-size: 15px;
 34         line-height: 1.4em;
 35         display: block;
 36          !important;
 37     }
 38 
 39     pre code {
 40         white-space: pre;
 41         overflow: auto;
 42         border-radius: 3px;
 43         padding: 1px 1px;
 44         display: block !important;
 45     }
 46 
 47     strong,
 48     b {
 49         color: #BF360C;
 50     }
 51 
 52     em,
 53     i {
 54         color: #009688;
 55     }
 56 
 57     hr {
 58         border: 1px solid #BF360C;
 59         margin: 1.5em auto;
 60     }
 61 
 62     p {
 63         margin: 1.5em 5px !important;
 64     }
 65 
 66     table,
 67     pre,
 68     dl,
 69     blockquote,
 70     q,
 71     ul,
 72     ol {
 73         margin: 10px 5px;
 74     }
 75 
 76     ul,
 77     ol {
 78         padding-left: 15px;
 79     }
 80 
 81     li {
 82         margin: 10px;
 83     }
 84 
 85     li p {
 86         margin: 10px 0 !important;
 87     }
 88 
 89     ul ul,
 90     ul ol,
 91     ol ul,
 92     ol ol {
 93         margin: 0;
 94         padding-left: 10px;
 95     }
 96 
 97     ul {
 98         list-style-type: circle;
 99     }
100 
101     dl {
102         padding: 0;
103     }
104 
105     dl dt {
106         font-size: 1em;
107         font-weight: bold;
108         font-style: italic;
109     }
110 
111     dl dd {
112         margin: 0 0 10px;
113         padding: 0 10px;
114     }
115 
116     blockquote,
117     q {
118         border-left: 2px solid #009688;
119         padding: 0 10px;
120         color: #777;
121         quotes: none;
122         margin-left: 1em;
123     }
124 
125     blockquote::before,
126     blockquote::after,
127     q::before,
128     q::after {
129         content: none;
130     }
131 
132     h1,
133     h2,
134     h3,
135     h4,
136     h5,
137     h6 {
138         margin: 20px 0 10px;
139         padding: 0;
140         font-style: bold !important;
141         color: #009688 !important;
142         text-align: center !important;
143         margin: 1.5em 5px !important;
144         padding: 0.5em 1em !important;
145     }
146 
147     h1 {
148         font-size: 24px !important;
149         border-bottom: 1px solid #ddd !important;
150     }
151 
152     h2 {
153         font-size: 20px !important;
154         border-bottom: 1px solid #eee !important;
155     }
156 
157     h3 {
158         font-size: 18px;
159     }
160 
161     h4 {
162         font-size: 16px;
163     }
164 
165 
166     table {
167         padding: 0;
168         border-collapse: collapse;
169         border-spacing: 0;
170         font-size: 1em;
171         font: inherit;
172         border: 0;
173         margin: 0 auto;
174     }
175 
176     tbody {
177         margin: 0;
178         padding: 0;
179         border: 0;
180     }
181 
182     table tr {
183         border: 0;
184         border-top: 1px solid #CCC;
185         background-color: white;
186         margin: 0;
187         padding: 0;
188     }
189 
190     table tr:nth-child(2n) {
191         background-color: #F8F8F8;
192     }
193 
194     table tr th,
195     table tr td {
196         font-size: 16px;
197         border: 1px solid #CCC;
198         margin: 0;
199         padding: 5px 10px;
200     }
201 
202     table tr th {
203         font-weight: bold;
204         color: #eee;
205         border: 1px solid #009688;
206         background-color: #009688;
207     }
208     </style>
209     <style>
210     #area>table {
211         width: 100%;
212         table-layout: fixed;
213     }
214 
215     #area table tr td {
216         margin: 0;
217         padding: 6px;
218         border: 0;
219 
220     }
221 
222 
223     #md-area {
224 
225         width: 100%;
226         height: 600px;
227         font-size: 18px;
228         overflow: hidden;
229         font-weight: bold;
230         outline: none;
231     }
232 
233     #show-area {
234         height: 600px;
235         background-color: #FCF6E5;
236     }
237 
238     .clearfix:before {
239         content: "";
240         display: table;
241     }
242     </style>
243     <script>
244     function mdSwitch() {
245         var mdValue = document.getElementById("md-area").value;
246         var converter = new showdown.Converter();
247         var html = converter.makeHtml(mdValue);
248         document.getElementById("show-area").innerHTML = html;
249     }
250     </script>
251     <div id="area">
252         <table>
253             <tr>
254                 <td><textarea name="" id="md-area" onkeyup=mdSwitch()></textarea></td>
255                 <td>
256                     <div id="show-area" class="clearfix"></div>
257                 </td>
258             </tr>
259         </table>
260     </div>
261 </body>
262 
263 </html>

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36.筛选数组数据

<script type="text/javascript">
    //建立数组
    var  arr = ['*','##',"***","&&","****","##*"];
    arr[7] = "**";
    //数组长度
    var l = arr.length;
    
    //删除数组中非*的项
  
    for(var i = 0; i < l; i++){
        var val = arr[i];

        if(val != undefined) {
            var newarr = val.split('');
            var newl = newarr.length;
            for(var j = 0; j < newl; j++){
                if(newarr[j] != '*'){
                    arr.splice(i, 1);
                    break;
                }
            }
        }
    }

    //按照字符数排序
    arr.sort(function(a, b){
        if(a.length > b.length){
            return 1
        }else if(a.length < b.length){
            return -1
        }else{
            return 0
        }
    })
    
 
    //将数组内容输出，完成达到的效果。
    for(var i = 0; i < l; i++){
        if(arr[i] != undefined){
        document.write(arr[i] + '<br />')
        }
    }
</script>

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<script type="text/javascript">

 //第一步把以前的数据写成一个数组的形式,定义变量为 infos
 var infos=[
    ['小A','女',21,'大一'],
    ['小B','男',23,'大三'],
    ['小C','男',24,'大四'],
    ['小C','男',24,'大四'],
    ['小D','女',21,'大一'],
    ['小E','女',22,'大四'],
    ['小F','男',21,'大一'],
    ['小G','女',22,'大二'],
    ['小H','女',20,'大三'],
    ['小I','女',20,'大一'],
    ['小J','男',20,'大三']
     ];
 
 //第一次筛选，找出都是大一的信息
 var i=0;
 var length=infos.length;
 for(i=0;i<length;i++){
    if(infos[i][3]=='大一'&&infos[i][1]=='女'){
        document.write(infos[i][0] + "&nbsp&nbsp"+ infos[i][3]+"</br>");
    }
    
 }
 
 //第二次筛选，找出都是女生的信息
 
 
  
</script>

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37.简单加减乘除计算器

 1 <!DOCTYPE html>
 2 <html>
 3  <head>
 4   <title>加减乘除计算器</title>  
 5   <script type="text/javascript">
 6    function count(){
 7        
 8     //获取第一个输入框的值
 9     var a=document.getElementById("txt1").value;
10     //获取第二个输入框的值
11     var b=document.getElementById("txt2").value;
12     //获取选择框的值
13     var c=document.getElementById("select").value;
14     var sum="";
15     switch(c)
16     {
17       case '+':
18       sum=parseFloat(a) + parseFloat(b);
19       break;
20       case '-':
21       sum=parseFloat(a) - parseFloat(b);
22       break;
23       case '*':
24       sum=parseFloat(a) * parseFloat(b);
25       break;
26       default:
27       sum=parseFloat(a) / parseFloat(b);
28       break;
29     
30     }
31     document.getElementById("fruit").value=sum;
32    }
33   </script> 
34  </head> 
35  <body>
36    <input type='text' id='txt1' /> 
37    <select id='select'>
38         <option value='+'>+</option>
39         <option value="-">-</option>
40         <option value="*">*</option>
41         <option value="/">/</option>
42    </select>
43    <input type='text' id='txt2' /> 
44    <input type='button' value=' = ' onclick="count()" /> <!--经过 = 按钮来调用建立的函数，获得结果--> 
45    <input type='text' id='fruit' />   
46  </body>
47 </html>

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38.js实现随机选取10——100之间的10个数字

var iArray=[];

function getRandom(istart,iend){
        var iChoice=istart-iend+1;

        return Math.floor(Math.random()*iChoice+istart);
}

for(var i=0;i<10;i++){


        iArray.push(getRandom(10,100));


}

iArray.sort()

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39.删除数组中的null、undefined以及empty值

var a=[123, undefined, undefined, undefined, 8567, 213];
var b = [];//去除undefined后的结果

for(var i=0;i<a.length;i++){
    if(typeof(a[i])!='undefined'){ //或者a[i]!='undefined'
        b.push(a[i]);
    }
}

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/*1只删除存在undefined和empty(空数组)的数组*/
let arr1 = [123, undefined, undefined, undefined, 8567, empty, 213];
//empty不能直接设置,是经过delete arr1[5]来产生的

arr2 = arr1.filter(function(item,index,arr){
    return typeof arr[index] != 'undefined'
})
//[123, 8567, 213]


/*2.只删除存在有null的数组*/
let arr1 = [533, 213, null, 237, empty, 789];

arr2 = arr1.filter(function(item,index,arr){
    return arr[index] != null
})
// [533, 213, 237, 789]


/*3.同时删除存在undefined、empty以及null的数组*/

let arr1 = [123, undefined, empty, 8567, null, null, 213];
let arr2 = [];

for(let i =0;i<arr1.length;i++){
    if(arr1[i]!=undefined || arr1[i]!=null)  //注意undefined不能加引号
        arr2.push(arr1[i])
}
//[123, 8567, 213]

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待续......node