前端之JS(四)
DOM Event(事件)
事件类型
onclick 当用户点击某个对象时调用的事件句柄。 ondblclick 当用户双击某个对象时调用的事件句柄。 onfocus 元素获得焦点。 练习:输入框 onblur 元素失去焦点。 应用场景:用于表单验证,用户离开某个输入框时,代表已经输入完了,我们可以对它进行验证. onchange 域的内容被改变。 应用场景:通常用于表单元素,当元素内容被改变时触发.(三级联动) onkeydown 某个键盘按键被按下。 应用场景: 当用户在最后一个输入框按下回车按键时,表单提交. onkeypress 某个键盘按键被按下并松开。 onkeyup 某个键盘按键被松开。
onload 一张页面或一幅图像完成加载。
onmousedown 鼠标按钮被按下。 onmousemove 鼠标被移动。 onmouseout 鼠标从某元素移开。 onmouseover 鼠标移到某元素之上。 onmouseleave 鼠标从元素离开 onselect 文本被选中。 onsubmit 确认按钮被点击。
绑定事件方式
方式1:
<div id="div" onclick="foo(this)">点我呀</div>
<script>
    function foo(self){           // 形参不能是this;
        console.log("点你大爷!");
        console.log(self);   
    }
</script>
方式2:
<p id="abc">试一试!</p>
<script>
    var ele=document.getElementById("abc");
    ele.onclick=function(){
        console.log("ok");
        console.log(this);    // this直接用
    };
</script>
事件介绍
1、onload:
onload 属性开发中 只给 body元素加.这个属性的触发 标志着 页面内容被加载完成.应用场景: 当有些事情我们希望页面加载完立刻执行,那么可以使用该事件属性.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
         /*
              window.onload=function(){
                   var ele=document.getElementById("ppp");
                   ele.onclick=function(){
                   alert(123)
                };
             };
         
         */
          function fun() {
              var ele=document.getElementById("ppp");
               ele.onclick=function(){
                alert(123)
            };
          }
    </script>
</head>
<body onload="fun()">
<p id="ppp">hello p</p>
</body>
</html>
2、onsubmit:
当表单在提交时触发. 该属性也只能给form元素使用.应用场景: 在表单提交前验证用户输入是否正确.如果验证失败.在该方法中我们应该阻止表单的提交.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        window.onload=function(){
            //阻止表单提交方式1().
            //onsubmit 命名的事件函数,可以接受返回值. 其中返回false表示拦截表单提交.其他为放行.
             var ele=document.getElementById("form");
             ele.onsubmit=function(event) {
            //    alert("验证失败 表单不会提交!");
            //    return false;
            // 阻止表单提交方式2 event.preventDefault(); ==>通知浏览器不要执行与事件关联的默认动作。
             alert("验证失败 表单不会提交!");
             event.preventDefault();
    }
        };
    </script>
</head>
<body>
<form id="form">
            <input type="text"/>
            <input type="submit" value="点我!" />
</form>
</body>
</html>
3、事件传播:

<div id="abc_1" style="border:1px solid red;width:300px;height:300px;">
        <div id="abc_2" style="border:1px solid red;width:200px;height:200px;">
        </div>
</div>
<script type="text/javascript">
        document.getElementById("abc_1").onclick=function(){
            alert('111');
        };
        document.getElementById("abc_2").onclick=function(event){
            alert('222');
            event.stopPropagation(); //阻止事件向外层div传播.
        }
</script>
4、onselect:

<input type="text">
<script>
    var ele=document.getElementsByTagName("input")[0];
    ele.onselect=function(){
          alert(123);
    }
</script>
5、onchange:

<select name="" id="">
    <option value="">111</option>
    <option value="">222</option>
    <option value="">333</option>
</select>
<script>
    var ele=document.getElementsByTagName("select")[0];
    ele.onchange=function(){
          alert(123);
    }
</script>
6、onkeydown:
Event 对象:Event 对象代表事件的状态,比如事件在其中发生的元素、键盘按键的状态、鼠标的位置、鼠标按钮的状态。
事件通常与函数结合使用,函数不会在事件发生前被执行!event对象在事件发生时系统已经创建好了,并且会在事件函数被调用时传给事件函数.我们获得仅仅需要接收一下即可.比如onkeydown,我们想知道哪个键被按下了,需要问下event对象的属性,这里就时KeyCode.

<input type="text" id="t1"/>
<script type="text/javascript">
    var ele=document.getElementById("t1");
    ele.onkeydown=function(e){
        e=e||window.event;
        var keynum=e.keyCode;
        var keychar=String.fromCharCode(keynum);
        alert(keynum+'----->'+keychar);
    };
</script>
7、onmouseout与onmouseleave事件的区别:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #container{
            width: 300px;
        }
        #title{
            cursor: pointer;
            background: #ccc;
        }
       #list{
           display: none;
           background:#fff;
       }
        #list div{
            line-height: 50px;
        }
        #list  .item1{
            background-color: green;
        }
         #list  .item2{
            background-color: rebeccapurple;
        }
         #list  .item3{
            background-color: lemonchiffon;
        }
    </style>
</head>
<body>
<p>先看下使用mouseout的效果:</p>
<div id="container">
        <div id="title">使用了mouseout事件↓</div>
        <div id="list">
                <div class="item1">第一行</div>
                <div class="item2">第二行</div>
                <div class="item3">第三行</div>
        </div>
</div>
<script>
// 1.不论鼠标指针离开被选元素还是任何子元素,都会触发 mouseout 事件。
// 2.只有在鼠标指针离开被选元素时,才会触发 mouseleave 事件。
   var container=document.getElementById("container");
   var title=document.getElementById("title");
   var list=document.getElementById("list");
   title.onmouseover=function(){
       list.style.display="block";
   };
   container.onmouseleave=function(){  // 改为mouseout试一下
       list.style.display="none";
   };
/*
因为mouseout事件是会冒泡的,也就是onmouseout事件可能被同时绑定到了container的子元素title和list
上,所以鼠标移出每个子元素时也都会触发我们的list.style.display="none";
*/
  /*
  思考:
  if:
       list.onmouseout=function(){
           list.style.display="none";
   };
     为什么移出第一行时,整个list会被隐藏?
     其实是同样的道理,onmouseout事件被同时绑定到list和它的三个子元素item上,所以离开任何一个
     子元素同样会触发list.style.display="none";
   */
</script>
</body>
</html>
实例
1、搜索框

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
<script>
function Focus(){
    var input=document.getElementById("ID1");
    if (input.value=="请输入用户名"){
        input.value="";
    }
}
function Blurs(){
    var ele=document.getElementById("ID1");
    var val=ele.value;
    if(!val.trim()){
        ele.value="请输入用户名";
    }
}
</script>
</head>
<body>
    <input id="ID1" type="text" value="请输入用户名" onblur="Blurs()" onfocus="Focus()">
</body>
</html>
2、模态对话框

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .back{
            background-color: white;
            height: 2000px;
        }
        .shade{
            position: fixed;
            top: 0;
            bottom: 0;
            left:0;
            right: 0;
            background-color: grey;
            opacity: 0.4;
        }
        .hide{
            display: none;
        }
        .models{
            position: fixed;
            top: 50%;
            left: 50%;
            margin-left: -100px;
            margin-top: -100px;
            height: 200px;
            width: 200px;
            background-color: wheat;
        }
    </style>
</head>
<body>
<div class="back">
    <input class="c" type="button" value="click">
</div>
<div class="shade hide handles"></div>
<div class="models hide handles">
    <input class="c" type="button" value="cancel">
</div>
<script>
    var eles=document.getElementsByClassName("c");
    var handles=document.getElementsByClassName("handles");
    for(var i=0;i<eles.length;i++){
        eles[i].onclick=function(){
            if(this.value=="click"){
                for(var j=0;j<handles.length;j++){
                    handles[j].classList.remove("hide");
                 }
            }
            else {
                for(var j=0;j<handles.length;j++){
                    handles[j].classList.add("hide");
                }
            }
        }
    }
</script>
</body>
</html>
3、表格案例

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<button class="select_all">全选</button>
<button class="select_reverse">反选</button>
<button class="cancel">取消</button>
<hr>
<table class="server_table" border="2px" cellspacing="2px">
    <tr>
        <td><input type="checkbox" class="item"></td>
        <td>111</td>
        <td>111</td>
        <td>111</td>
    </tr>
    <tr>
        <td><input type="checkbox" class="item"></td>
        <td>222</td>
        <td>222</td>
        <td>222</td>
    </tr>
    <tr>
        <td><input type="checkbox" class="item"></td>
        <td>333</td>
        <td>333</td>
        <td>333</td>
    </tr>
    <tr>
        <td><input type="checkbox" class="item"></td>
        <td>444</td>
        <td>444</td>
        <td>444</td>
    </tr>
</table>
<script>
/*
    var ele_all=document.getElementsByClassName("select_all")[0];
    var ele_reverse=document.getElementsByClassName("select_reverse")[0];
    var ele_cancel=document.getElementsByClassName("cancel")[0];
    var input_arr=document.getElementsByClassName("item");
    ele_all.onclick=function(){
          for(var i=0;i<input_arr.length;i++){
              console.log(input_arr[i]);
              var input=input_arr[i];
              input.checked=true;
          }
    };
     ele_cancel.onclick=function(){
          for(var i=0;i<input_arr.length;i++){
              console.log(input_arr[i]);
              var input=input_arr[i];
              input.checked=false;
          }
    };
    ele_reverse.onclick=function(){
          for(var i=0;i<input_arr.length;i++){
              console.log(input_arr[i]);
              var input=input_arr[i];
              if(input.checked){
                  input.checked=false;
              }
              else{
                  input.checked=true;
              }
          }
    };
*/
    var input_arr=document.getElementsByClassName("item");
    var button_arr=document.getElementsByTagName("button");
    for(var i=0;i<button_arr.length;i++){
        button_arr[i].onclick=function(){
            for (var j=0;j<input_arr.length;j++){
                 var inp=input_arr[j]
                 if(this.innerText=="全选"){
                     console.log("ok");
                 inp.checked=true;
             }
            else if(this.innerText=="取消"){
                  inp.checked=false;
             }
            else {
                 if(inp.checked){
                     inp.checked=false;
                 }else {
                     inp.checked=true;
                 }
             }
                
            }
        }
    }
</script>
</body>
</html>
4、select移动

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .outer{
            margin: 0 auto;
            background-color: darkgray;
            width: 80%;
            height: 600px;margin-top: 30px;
            word-spacing: -5px;
        }
        #left{
            display: inline-block;
            width: 100px ;
            height: 140px;
            background-color: wheat;
            text-align: center;
        }
        #choice{
            display: inline-block;
            height: 140px;
            background-color: darkolivegreen;
            vertical-align: top;
            padding:0 5px;
        }
        #choice button{
            margin-top: 20px;
        }
         #right{
            display: inline-block;
            width: 100px ;
            height: 140px;
            background-color: wheat;
            text-align: center;
            line-height: 140px;
        }
    </style>
</head>
<body>
<div class="outer">
    <select multiple="multiple" size="5" id="left">
    <option>红楼梦</option>
    <option>西游记</option>
    <option>水浒传</option>
    <option>JinPingMei</option>
    <option>三国演义</option>
</select>
<span id="choice">
    <button id="choose_move"> > </button><br>
    <button id="all_move"> >> </button>
</span>
<select multiple="multiple" size="10" id="right">
    <option>放风筝的人</option>
</select>
</div>
<script>
    var choose_move=document.getElementById("choose_move");
    var all_move=document.getElementById("all_move");
    var right=document.getElementById("right");
    var left=document.getElementById("left");
    var options=left.options;
    choose_move.onclick=function(){
        for (var i=0; i<options.length;i++){
             var option=options[i];
             if(option.selected==true){
                   // var news=option.cloneNode(true);
                   // console.log(news);
                   right.appendChild(option);
                   i--;
             }
         }
    };
    all_move.onclick=function(){
        for (var i=0; i<options.length;i++){
             var option=options[i];
                   right.appendChild(option);
                   i--;
         };
    };
    /*
   var buttons=document.getElementsByTagName("button");
   for(var i=0;i<buttons.length;i++) {
        buttons[i].onclick = function () {
            for (var i = 0; i < options.length; i++) {
                var option = options[i];
                if (this.innerText == ">") {
                    if (option.selected == true) {
                        // var news=option.cloneNode(true);
                        // console.log(news);
                        right.appendChild(option);
                        i--;
                    }
                } else {
                    right.appendChild(option);
                    i--;
                }
            }
        };
    }
   */
</script>
</body>
</html>
5、二级联动

<select id="province">
    <option>请选择省:</option>
</select>
<select id="city">
    <option>请选择市:</option>
</select>
<script>
    data={"河北省":["廊坊","邯郸"],"北京":["朝阳区","海淀区"]};
      var p=document.getElementById("province");
      var c=document.getElementById("city");
    
    for(var i in data){
        var option_pro=document.createElement("option");
        option_pro.innerHTML=i;
        p.appendChild(option_pro);
    }
     p.onchange=function(){
            pro=(this.options[this.selectedIndex]).innerHTML;
            citys=data[pro];
         c.options.length=0;
         for (var i in citys){
             var option_city=document.createElement("option");
             option_city.innerHTML=citys[i];
             c.appendChild(option_city);
         }
        }
</script>
6、跑马灯与tab切换

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>tab</title>
  <style>
    *{margin:0; padding:0; list-style:none;}
    body{
        font-family: "Helvetica Neue", "Hiragino Sans GB", "Microsoft YaHei", "\9ED1\4F53", Arial, sans-serif;
    }
    h3{
        text-align: center;
        color:darkcyan;
        margin-top: 30px;
        letter-spacing: 5px;
    }
    .box{
      width: 1000px;
      margin:50px auto 0px;
    }
    #title{
      line-height: 40px;
      background-color: rgb(247,247,247);
      font-size: 16px;
      font-weight: bold;
      color: rgb(102,102,102);
    }
    #title span{
      float: left;
      width: 166px;
      text-align: center;
    }
    #title span:hover{
      /*color: black;*/
      cursor: pointer;
    }
    #content{
      margin-top: 20px;
    }
    #content li{
      width: 1050px;
      display: none;
      background-color: rgb(247,247,247);
    }
    #content li div{
      width: 156px;
      margin-right: 14px;
      float: left;
      text-align: center;
    }
    #content li div a{
      font-size: 14px;
      color: black;
      line-height: 14px;
    /*  float: left;*/
    display: inline-block;
      margin-top: 10px;
    }
    #content li a:hover{
      color: #B70606;
    }
    #content li div span{
        font-size: 16px;
        line-height: 16px;
        /*float: left;*/
        display: block;
        color: rgb(102,102,102);
        margin-top: 10px;
      }
    #content img{
      float: left;
      width: 155px;
      height: 250px;
    }
    #title .select{
      background-color: #2459a2;
      color: white;
        border-radius: 10%;
    }
    #content .show{
      display: block;
    }
    .show span{
        color: red!important;
        font-size: 30px;
    }
  </style>
</head>
<body>
    <h3 id="wel">京东商城欢迎您</h3>
    <!--  direction="right up down left" -->
<!--  behavior:滚动方式(包括3个值:scroll、slide、alternate) -->
<!--  说明:scroll:循环滚动,默认效果;slide:只滚动一次就停止;alternate:来回交替进行滚动。 -->
<!--  scrollamount="5" 滚动速度 -->
<marquee behavior="scroll" direction="right">欢迎您苑昊先生</marquee>
    <script>
    function test(){
        var mywel = document.getElementById("wel");
        var content = mywel.innerText;
        var f_content = content.charAt(0);
        var l_content = content.substring(1,content.length);
        var new_content = l_content + f_content;
        mywel.innerText = new_content;
    }
    // setInterval("test();", 500);
</script>
    <div class="box">
      <p id="title">
        <span class="select">家用电器</span>
        <span>家具</span>
        <span>汽车</span>
        <span>食品</span>
        <span>女鞋</span>
        <span>医疗保健</span>
      </p>
      <ul id="content">
        <li class="show">
          <div><img src="https://img10.360buyimg.com/n1/s450x450_jfs/t4786/325/2470647304/119102/9e1a4ed5/59005841Nd786a8df.jpg" alt="冰箱"><a href="#">容声(Ronshen)冰箱</a><span>价格:5600</span></div>
          <div><img src="https://img12.360buyimg.com/n1/s450x450_jfs/t3037/347/1290968859/201366/7c1028a0/57c00194N9d0a54c6.jpg" alt="洗衣机"><a href="#">海尔洗衣机</a><span>价格:5400</span></div>
          <div><img src="https://img11.360buyimg.com/n1/jfs/t3289/128/2393835119/236360/af1d283b/57e0f300N53dde603.jpg" alt="电饭煲"><a href="#">福库(CUCKOO)电饭煲</a><span>价格:3999</span></div>
          <div><img src="https://img13.360buyimg.com/n1/jfs/t3235/137/2361713777/152258/a6908440/57e098c2N44a90a5d.jpg" alt="智能电视"><a href="#">三星智能电视</a><span>价格:8999</span></div>
          <div><img src="https://img10.360buyimg.com/n1/jfs/t2053/101/1391591157/215066/572e131b/5696ee9bN2376492d.jpg" alt="净水器"><a href="#">净水器</a><span>价格:1300</span></div>
          <div><img src="https://img14.360buyimg.com/n1/jfs/t3175/78/2357430273/262835/9a8e7f65/57e0a3e9Nbda39dd2.jpg" alt="空气净化器"><a href="#">空气净化器</a><span>价格:5300</span></div>
        </li>
        <li>
          <div><img src="https://img12.360buyimg.com/n1/jfs/t1948/172/2877517581/556924/682eb107/56f63dc8Naddf77e5.jpg" alt="沙发"><a href="#">沙发</a><span>价格:2900</span></div>
          <div><img src="https://img12.360buyimg.com/n1/jfs/t1948/172/2877517581/556924/682eb107/56f63dc8Naddf77e5.jpg" alt="沙发"><a href="#">沙发</a><span>价格:2900</span></div>
          <div><img src="https://img12.360buyimg.com/n1/jfs/t1948/172/2877517581/556924/682eb107/56f63dc8Naddf77e5.jpg" alt="沙发"><a href="#">沙发</a><span>价格:2900</span></div>
          <div><img src="https://img12.360buyimg.com/n1/jfs/t1948/172/2877517581/556924/682eb107/56f63dc8Naddf77e5.jpg" alt="沙发"><a href="#">沙发</a><span>价格:2900</span></div>
          <div><img src="https://img12.360buyimg.com/n1/jfs/t1948/172/2877517581/556924/682eb107/56f63dc8Naddf77e5.jpg" alt="沙发"><a href="#">沙发</a><span>价格:2900</span></div>
          <div><img src="https://img12.360buyimg.com/n1/jfs/t1948/172/2877517581/556924/682eb107/56f63dc8Naddf77e5.jpg" alt="沙发"><a href="#">沙发</a><span>价格:2900</span></div>
        </li>
        <li>
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          <div><img src="http://img11.360buyimg.com/n1/jfs/t4969/76/45396935/144539/347153d4/58d9cff4N36872ad6.jpg" alt="长安汽车"><a href="#">长安汽车</a><span>价格:12900</span></div>
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          <div><img src="http://img11.360buyimg.com/n1/jfs/t4969/76/45396935/144539/347153d4/58d9cff4N36872ad6.jpg" alt="长安汽车"><a href="#">长安汽车</a><span>价格:12900</span></div>
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          <div><img src="https://img14.360buyimg.com/n1/jfs/t4414/110/2582917360/207971/b7e129ad/58f0ee1fN94425de1.jpg" alt="嘉兴粽子"><a href="#">嘉兴粽子</a><span>价格:1</span></div>
          <div><img src="https://img14.360buyimg.com/n1/jfs/t4414/110/2582917360/207971/b7e129ad/58f0ee1fN94425de1.jpg" alt="嘉兴粽子"><a href="#">嘉兴粽子</a><span>价格:1</span></div>
          <div><img src="https://img14.360buyimg.com/n1/jfs/t4414/110/2582917360/207971/b7e129ad/58f0ee1fN94425de1.jpg" alt="嘉兴粽子"><a href="#">嘉兴粽子</a><span>价格:1</span></div>
          <div><img src="https://img14.360buyimg.com/n1/jfs/t4414/110/2582917360/207971/b7e129ad/58f0ee1fN94425de1.jpg" alt="嘉兴粽子"><a href="#">嘉兴粽子</a><span>价格:1</span></div>
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          <div><img src="https://img14.360buyimg.com/n1/jfs/t3079/298/5759209435/92674/14818594/587f1c33N53e5d2a9.jpg" alt="星期六"><a href="#">星期六</a><span>价格:439</span></div>
          <div><img src="https://img14.360buyimg.com/n1/jfs/t3079/298/5759209435/92674/14818594/587f1c33N53e5d2a9.jpg" alt="星期六"><a href="#">星期六</a><span>价格:439</span></div>
          <div><img src="https://img14.360buyimg.com/n1/jfs/t3079/298/5759209435/92674/14818594/587f1c33N53e5d2a9.jpg" alt="星期六"><a href="#">星期六</a><span>价格:439</span></div>
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          <div><img src="https://img12.360buyimg.com/n1/jfs/t5755/127/1139389729/356866/99d4e869/5923e410Nb2983f70.jpg" alt="汇仁 肾宝片"><a href="#">汇仁 肾宝片</a><span>价格:322</span></div>
          <div><img src="https://img12.360buyimg.com/n1/jfs/t5755/127/1139389729/356866/99d4e869/5923e410Nb2983f70.jpg" alt="汇仁 肾宝片"><a href="#">汇仁 肾宝片</a><span>价格:322</span></div>
          <div><img src="https://img12.360buyimg.com/n1/jfs/t5755/127/1139389729/356866/99d4e869/5923e410Nb2983f70.jpg" alt="汇仁 肾宝片"><a href="#">汇仁 肾宝片</a><span>价格:322</span></div>
          <div><img src="https://img12.360buyimg.com/n1/jfs/t5755/127/1139389729/356866/99d4e869/5923e410Nb2983f70.jpg" alt="汇仁 肾宝片"><a href="#">汇仁 肾宝片</a><span>价格:322</span></div>
          <div><img src="https://img12.360buyimg.com/n1/jfs/t5755/127/1139389729/356866/99d4e869/5923e410Nb2983f70.jpg" alt="汇仁 肾宝片"><a href="#">汇仁 肾宝片</a><span>价格:322</span></div>
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