function Human(name){
    this.name = name
}
Human.prototype.run = function(){
    console.log("我叫"+this.name+"，我在跑")
    return undefined
}
function Man(name){
    Human.call(this, name)
    this.gender = '男'
}

var f = function(){}
f.prototype = Human.prototype
Man.prototype = new f()
//上面三行等价于Man.prototype.__proto__ = Human.prototype
//但直接修改__proto__开销很高

Man.prototype.fight = function(){
    console.log('糊你熊脸')
}

class Human{
    constructor(name){
        this.name = name
    }
    run(){
        console.log("我叫"+this.name+"，我在跑")
        return undefined
    }
}
class Man extends Human{
    constructor(name){
        super(name)
        this.gender = '男'
    }
    fight(){
        console.log('糊你熊脸')
    }
}

window.addEventListener('scroll', callback);

(function () {
  var throttle = function (type, name, obj) {
    var obj = obj || window;
    var running = false;
    var func = function () {
      if (running) { return; }
      running = true;
      requestAnimationFrame(function() {
        obj.dispatchEvent(new CustomEvent(name));
        running = false;
      });
    };
    obj.addEventListener(type, func);
  };

  // 将 scroll 事件重定义为 optimizedScroll 事件
  throttle('scroll', 'optimizedScroll');
})();

window.addEventListener('optimizedScroll', function() {
  console.log('Resource conscious scroll callback!');
});

(function() {
  window.addEventListener('scroll', scrollThrottler, false);

  var scrollTimeout;
  function scrollThrottler() {
    if (!scrollTimeout) {
      scrollTimeout = setTimeout(function () {
        scrollTimeout = null;
        actualScrollHandler();
      }, 66);
    }
  }

  function actualScrollHandler() {
    // ...
  }
}());

function throttle(fn, wait) {
  var time = Date.now();
  return function() {
    if ((time + wait - Date.now()) < 0) {
      fn();
      time = Date.now();
    }
  }
}

window.addEventListener('scroll', throttle(callback, 1000));

$('textarea').on('keydown', ajaxAction);

$('textarea').on('keydown', debounce(ajaxAction, 2500));

function debounce(fn, delay){
  var timer = null; // 声明计时器
  return function() {
    var context = this;
    var args = arguments;
    clearTimeout(timer);
    timer = setTimeout(function () {
      fn.apply(context, args);
    }, delay);
  };
}

// 避免在滚动时过分的更新定位
jQuery(window).on('scroll', _.throttle(updatePosition, 100));
 
// 点击后就调用 `renewToken`，但5分钟内超过1次。
var throttled = _.throttle(renewToken, 300000, { 'trailing': false });
jQuery(element).on('click', throttled);
 
// 取消一个 trailing 的节流调用。
jQuery(window).on('popstate', throttled.cancel);

// 避免窗口在变动时出现昂贵的计算开销。
jQuery(window).on('resize', _.debounce(calculateLayout, 150));
 
// 当点击时 `sendMail` 随后就被调用。
jQuery(element).on('click', _.debounce(sendMail, 300, {
  'leading': true,
  'trailing': false
}));
 
// 确保 `batchLog` 调用1次之后，1秒内会被触发。
var debounced = _.debounce(batchLog, 250, { 'maxWait': 1000 });
var source = new EventSource('/stream');
jQuery(source).on('message', debounced);
 
// 取消一个 trailing 的防抖动调用
jQuery(window).on('popstate', debounced.cancel);

var http = require('http')
var fs = require('fs')
var url = require('url')
var port = process.argv[2]

if(!port){
  console.log('请指定端口号\nnode server.js 8888 这样')
  process.exit(1)
}

var server = http.createServer(function(request, response){
  var parsedUrl = url.parse(request.url, true)
  var pathWithQuery = request.url 
  var queryString = ''
  if(pathWithQuery.indexOf('?') >= 0){ queryString = pathWithQuery.substring(pathWithQuery.indexOf('?')) }
  var path = parsedUrl.pathname
  var query = parsedUrl.query
  var method = request.method

  /******** 从这里开始看，上面不要看 ************/

  console.log('含查询字符串的路径\n' + pathWithQuery)

  if(path === '/'){
    let string = fs.readFileSync('./index.html', 'utf8')
    let cookies =  request.headers.cookie.split('; ') // ['email=1@', 'a=1', 'b=2']
    let hash = {} //将cookie存放到一个hash表中
    for(let i =0;i<cookies.length; i++){
      let parts = cookies[i].split('=')
      let key = parts[0]
      let value = parts[1]
      hash[key] = value 
    }
    let email = hash.sign_in_email
    let users = fs.readFileSync('./db/users', 'utf8')
    users = JSON.parse(users)
    let foundUser //确认服务器是否有此用户信息
    for(let i=0; i< users.length; i++){
      if(users[i].email === email){
        foundUser = users[i]
        break
      }
    }
    console.log(foundUser)
    if(foundUser){
      string = string.replace('__password__', foundUser.password)
    }else{
      string = string.replace('__password__', '不知道')
    }
    response.statusCode = 200
    response.setHeader('Content-Type', 'text/html;charset=utf-8')
    response.write(string)
    response.end()
  }else if(path === '/sign_up' && method === 'GET'){  //路由sign_up的逻辑
    let string = fs.readFileSync('./sign_up.html', 'utf8')
    response.statusCode = 200
    response.setHeader('Content-Type', 'text/html;charset=utf-8')
    response.write(string)
    response.end()
  }else if(path === '/sign_up' && method === 'POST'){
    readBody(request).then((body)=>{
      let strings = body.split('&') // ['email=1', 'password=2', 'password_confirmation=3']
      let hash = {} //将用户提交的信息存到一个hash表里
      strings.forEach((string)=>{
        // string == 'email=1'
        let parts = string.split('=') // ['email', '1']
        let key = parts[0]
        let value = parts[1]
        hash[key] = decodeURIComponent(value) // hash['email'] = '1'
      })
      let {email, password, password_confirmation} = hash
      if(email.indexOf('@') === -1){ //如果用户填写的邮箱地址不含有@
        response.statusCode = 400
        response.setHeader('Content-Type', 'application/json;charset=utf-8')
        response.write(`{
          "errors": {
            "email": "invalid"
          }
        }`)
      }else if(password !== password_confirmation){
        response.statusCode = 400
        response.write('password not match')
      }else{
        var users = fs.readFileSync('./db/users', 'utf8')
        try{
          users = JSON.parse(users) // []
        }catch(exception){
          users = []  //如果解析本地db文件失败则设置为空数组
        }
        let inUse = false //确定本地是否有相同账户邮箱名
        for(let i=0; i<users.length; i++){
          let user = users[i]
          if(user.email === email){
            inUse = true
            break;
          }
        }
        if(inUse){
          response.statusCode = 400
          response.write('email in use')
        }else{
          users.push({email: email, password: password})
          var usersString = JSON.stringify(users)
          fs.writeFileSync('./db/users', usersString)
          response.statusCode = 200
        }
      }
      response.end()
    })
  }else if(path==='/sign_in' && method === 'GET'){ //sign_in逻辑与sign_up类似
    let string = fs.readFileSync('./sign_in.html', 'utf8')
    response.statusCode = 200
    response.setHeader('Content-Type', 'text/html;charset=utf-8')
    response.write(string)
    response.end()
  }else if(path==='/sign_in' && method === 'POST'){
    readBody(request).then((body)=>{
      let strings = body.split('&') // ['email=1', 'password=2', 'password_confirmation=3']
      let hash = {}
      strings.forEach((string)=>{
        // string == 'email=1'
        let parts = string.split('=') // ['email', '1']
        let key = parts[0]
        let value = parts[1]
        hash[key] = decodeURIComponent(value) // hash['email'] = '1'
      })
      let {email, password} = hash
      var users = fs.readFileSync('./db/users', 'utf8')
      try{
        users = JSON.parse(users) // []
      }catch(exception){
        users = []
      }
      let found
      for(let i=0;i<users.length; i++){
        if(users[i].email === email && users[i].password === password){
          found = true
          break
        }
      }
      if(found){
        response.setHeader('Set-Cookie', `sign_in_email=${email}`)
        response.statusCode = 200
      }else{
        response.statusCode = 401
      }
      response.end()
    })
  }else if(path==='/main.js'){
    let string = fs.readFileSync('./main.js', 'utf8')
    response.statusCode = 200
    response.setHeader('Content-Type', 'text/javascript;charset=utf-8')
    response.write(string)
    response.end()
  }else{
    response.statusCode = 404
    response.setHeader('Content-Type', 'text/html;charset=utf-8')
    response.write(`
      {
        "error": "not found"
      }
    `)
    response.end()
  }

  /******** 代码结束，下面不要看 ************/
})

function readBody(request){
  return new Promise((resolve, reject)=>{
    let body = []
    request.on('data', (chunk) => {
      body.push(chunk);
    }).on('end', () => {
      body = Buffer.concat(body).toString();
      resolve(body)
    })
  })
}

server.listen(port)
console.log('监听 ' + port + ' 成功\n请打开 http://localhost:' + port)

<body>
  <div class="form-wrapper">
    <h1>注册</h1>
    <form id="signUpForm">
      <div class="row">
        <label>邮箱</label>
        <input type="text" name="email">
        <span class="error"></span>
      </div>
      <div class="row">
        <label>密码</label>
        <input type="password" name="password">
        <span class="error"></span>
      </div>
      <div class="row">
        <label>确认密码</label>
        <input type="password" name="password_confirmation">
        <span class="error"></span>
      </div>
      <div class="row">
        <input type="submit" value="注册">
      </div>
    </form>
  </div>
  <script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>
  <script>
    let $form = $('#signUpForm')
    $form.on('submit', (e)=>{
      e.preventDefault()
      let hash = {}
      let need = ['email', 'password', 'password_confirmation']
      need.forEach((name)=>{
        let value = $form.find(`[name=${name}]`).val()
        hash[name] = value
      })
      $form.find('.error').each((index, span)=>{
        $(span).text('')
      })
      if(hash['email'] === ''){
        $form.find('[name="email"]').siblings('.error')
          .text('填邮箱呀同学')
        return
      }
      if(hash['password'] === ''){
        $form.find('[name="password"]').siblings('.error')
          .text('填密码呀同学')
        return
      }
      if(hash['password_confirmation'] === ''){
        $form.find('[name="password_confirmation"]').siblings('.error')
          .text('确认密码呀同学')
        return
      }
      if(hash['password'] !== hash['password_confirmation']){
        $form.find('[name="password_confirmation"]').siblings('.error')
          .text('密码不匹配')
        return
      }
      $.post('/sign_up', hash)  
        .then((response)=>{
          console.log(response)
        }, (request)=>{
          let {errors} = request.responseJSON
          if(errors.email && errors.email === 'invalid'){
            $form.find('[name="email"]').siblings('.error')
              .text('邮箱格式错误')
          }
        })
    })
  </script>
</body>

<body>
  <div class="form-wrapper">
    <h1>登录</h1>
    <form id="signInForm">
      <div class="row">
        <label>邮箱</label>
        <input type="text" name="email">
        <span class="error"></span>
      </div>
      <div class="row">
        <label>密码</label>
        <input type="password" name="password">
        <span class="error"></span>
      </div>
      <div class="row">
        <input type="submit" value="登录">
      </div>
    </form>
  </div>
  <script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>
  <script>
    let $form = $('#signInForm')
    $form.on('submit', (e)=>{ 
      e.preventDefault()  
      let hash = {}  
      let need = ['email', 'password']
      need.forEach((name)=>{
        let value = $form.find(`[name=${name}]`).val()
        hash[name] = value
      })
      $form.find('.error').each((index, span)=>{
        $(span).text('')
      })
      if(hash['email'] === ''){
        $form.find('[name="email"]').siblings('.error')
          .text('填邮箱呀同学')
        return
      }
      if(hash['password'] === ''){
        $form.find('[name="password"]').siblings('.error')
          .text('填密码呀同学')
        return
      }
      $.post('/sign_in', hash)  
        .then((response)=>{
          window.location.href = '/'
        }, (request)=>{
          alert('邮箱与密码不匹配')
        })
    })
  </script>
</body>

<body>
  <h1>你的密码是：__password__</h1>
</body>

.span{
    display:inline-block;
    width:4em;
    text-align:justify;
    overflow:hidden;
}
.span::after{
    content:"";
    display:inline-block;
    width:100%;
}

${
    overflow: hidden;  
    text-overflow: ellipsis;  
    display: -webkit-box;  
    -webkit-line-clamp: 3;  
    -webkit-box-orient: vertical; 
}

.clearfix:after{
    content: '';
    display: block;
    clear: both;
}
.clearfix{
    zoom: 1;
}

//at.alicdn.com/t/font_8d5l8fzk5b87iudi.js

<style type="text/css">
    .icon {
       width: 1em; height: 1em;
       vertical-align: -0.15em;
       fill: currentColor;
       overflow: hidden;
    }
</style>

<svg class="icon" aria-hidden="true">
    <use xlink:href="#icon-xxx"></use>
</svg>

body {
  background-color: #000000;
  background-image: url(data:image/png;base64,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); 
}

body, main::before { 
    background: url("tiger.jpg") 0 / cover fixed; 
} 
main { 
    position: relative; 
    background: hsla(0,0%,100%,.3); 
    overflow: hidden; 
} 
main::before { 
    content: ''; 
    position: absolute; 
    top: 0; right: 0; bottom: 0; left: 0; 
    filter: blur(20px); 
    margin: -30px; 
}

window.jQuery = function (nodeOrSelector) { //接受一个节点或者CSS选择器来找到目标
    let nodes = {} //初始化一个空的nodes对象，来存放获取到的目标对象
    if (typeof nodeOrSelector === 'string') {  //如果接受到的参数是CSS选择器
        let temp = document.querySelectorAll(nodeOrSelector) //通过DOM的querySelectorAll方法来找到目标对象存放到temp中
        for (let i = 0; i < temp.length; i++) { //遍历这个CSS选择器找到的所有目标
            nodes[i] = temp[i] // 将获取的伪数组的每个值一一存放到nodes对象中
        }
        nodes.length = temp.length //将获取到的伪数组的长度值赋给nodes对象的长度
    } else if (nodeOrSelector instanceof Node) { //如果接受到的参数是一个节点
        nodes = { //直接将改节点存放到nodes对象中
            0: nodeOrSelector, //有且仅有一个的值即节点本身
            length: 1 //对象只存了一个节点故长度为1
        }
    }
    nodes.addClass = function (classes) { //设置一个添加类名的函数addClass，可接受多个类名
        classes.forEach(value => { //多个类名通过数组存放，通过数组的forEach方法遍历类名数组的每一个值。
            for (let i = 0; i < nodes.length; i++) { //遍历获取到的每个节点
                nodes[i].classList.add(value) //将类名数组的每一个值都添加到目标节点的classList中
            }
        })
    }
    nodes.Text = function (text) { //设置一个获取文本或添加文本的函数Text
        if (text === undefined) { //如果用户没有提供参数，默认为获取目标节点中的文本
            var texts = [] //初始化一个空的数组对象，来存放文本
            for (let i = 0; i < node.length; i++) { //遍历获取到的每个节点
                texts.push(node[i].textContent) //通过DOM的textContent方法来获取节点中的文本，并通过数组的push方法将文本存到texts数组中
            }
            return texts //将存放完文本的texts数组返回给用户
        } else { //如果用户提供了参数，默认为将参数设置为目标节点中的文本
            for (let i = 0; i < nodes.length; i++) { //遍历获取到的每个节点
                nodes[i].textContent = text //通过DOM的textContent方法将用户提供的参数设置为节点中的文本。
            }
        }
    }
    return nodes //返回获取到的节点，提供给客户使用。
}

var 对象 = new 函数()
对象.__proto__ === 对象的构造函数.prototype

// 推论
var number = new Number()
number.__proto__ = Number.prototype
Number.__proto__ = Function.prototype // 因为 Number 是 Function 的实例

var object = new Object()
object.__proto__ = Object.prototype
Object.__proto__ = Function.prototype // 因为 Object 是 Function 的实例

var function = new Function()
function.__proto__ = Function.prototype
Function.__proto__ == Function.prototye // 因为 Function 是 Function 的实例！