【python】-- web开发之DOM

DOM

文档对象模型（Document Object Model，DOM）是一种用于HTML和XML文档的编程接口。它给文档提供了一种结构化的表示方法，可以改变文档的内容和呈现方式。我们最为关心的是，DOM把网页和脚本以及其他的编程语言联系了起来。DOM属于浏览器，而不是JavaScript语言规范里的规定的核心内容。

一、查找元素

1、直接查找

ocument.getElementById             根据ID获取一个标签
document.getElementsByName          根据name属性获取标签集合
document.getElementsByClassName     根据class属性获取标签集合
document.getElementsByTagName       根据标签名获取标签集合

2、间接查找、

parentNode          // 父节点
childNodes          // 所有子节点
firstChild          // 第一个子节点
lastChild           // 最后一个子节点
nextSibling         // 下一个兄弟节点
previousSibling     // 上一个兄弟节点


parentElement           // 父节点标签元素
children                // 所有子标签
firstElementChild       // 第一个子标签元素
lastElementChild        // 最后一个子标签元素
nextElementtSibling     // 下一个兄弟标签元素
previousElementSibling  // 上一个兄弟标签元素

二、元素操作

1、文本内容

innerText   文本
outerText
innerHTML   HTML内容
innerHTML  
value       值

2、属性

attributes                // 获取所有标签属性
setAttribute(key,value)   // 设置标签属性
getAttribute(key)         // 获取指定标签属性
 
/*
var atr = document.createAttribute("class");
atr.nodeValue="democlass";
document.getElementById('n1').setAttributeNode(atr);
*/

3、class操作

className                // 获取所有类名
classList.remove(value)    // 删除指定类
classList.add(value)       // 添加类

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
    <input type="button" value="全选"  onclick="CheckAll();"/>
    <input type="button" value="取消" onclick="CancelAll();"/>
    <input type="button" value="反选" onclick="ReverseCheck();"/>

    <table border="1" >
        <thead>

        </thead>
        <tbody id="tb">
            <tr>
                <td><input type="checkbox" /></td>
                <td>111</td>
                <td>222</td>
            </tr>
            <tr>
                <td><input type="checkbox" /></td>
                <td>111</td>
                <td>222</td>
            </tr>
            <tr>
                <td><input type="checkbox" /></td>
                <td>111</td>
                <td>222</td>
            </tr>
            <tr>
                <td><input type="checkbox" /></td>
                <td>111</td>
                <td>222</td>
            </tr>
        </tbody>
    </table>
    <script>
        function CheckAll(ths){
            var tb = document.getElementById('tb');
            var trs = tb.childNodes;
            for(var i =0; i<trs.length; i++){

                var current_tr = trs[i];
                if(current_tr.nodeType==1){
                    var inp = current_tr.firstElementChild.getElementsByTagName('input')[0];
                    inp.checked = true;
                }
            }
        }

        function CancelAll(ths){
            var tb = document.getElementById('tb');
            var trs = tb.childNodes;
            for(var i =0; i<trs.length; i++){

                var current_tr = trs[i];
                if(current_tr.nodeType==1){
                    var inp = current_tr.firstElementChild.getElementsByTagName('input')[0];
                    inp.checked = false;
                }
            }
        }

        function ReverseCheck(ths){
            var tb = document.getElementById('tb');
            var trs = tb.childNodes;
            for(var i =0; i<trs.length; i++){
                var current_tr = trs[i];
                if(current_tr.nodeType==1){
                    var inp = current_tr.firstElementChild.getElementsByTagName('input')[0];
                    if(inp.checked){
                        inp.checked = false;
                    }else{
                        inp.checked = true;
                    }
                }
            }
        }

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

demo

Demo-复选框全选/反选/取消

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .hide{
            display: none;
        }
        .c1{
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background-color: black;
            opacity: 0.6;
            z-index: 9;
        }
 
        .c2{
            width: 500px;
            height: 400px;
            background-color: white;
            position: fixed;
            left: 50%;
            top: 50%;
            margin-left: -250px;
            margin-top: -200px;
            z-index: 10;
        }
    </style>
</head>
<body style="margin: 0;">
    <div>
        <input type="button" value="添加" onclick="showModel();"/>
        <table border="1">
            <thead>
                <tr>
                    <th>主机名</th>
                    <th>端口</th>
                </tr>
            </thead>
            <tbody>
                <tr>
                    <td>192.168.1.1</td>
                    <td>8080</td>
                </tr>
            </tbody>
        </table>
    </div>
    <!--遮罩层开始-->
    <div id="i1" class="c1 hide"></div>
    <!--遮罩层开始-->
 
    <!--弹框层开始-->
    <div id="i2" class="c2 hide">
        <p><input type="text"/></p>
        <p><input type="text"/></p>
        <p>
            <input type="button" value="取消" onclick="hideModel()"/>
            <input type="button" value="确定"/>
        </p>
    </div>
    <!--弹框层结束-->
 
    <script>
        function showModel(){
            document.getElementById("i1").classList.remove("hide");
            document.getElementById("i2").classList.remove("hide");
        }
        function hideModel(){
            document.getElementById("i1").classList.add("hide");
            document.getElementById("i2").classList.add("hide");
        }
    </script>
</body>
</html>

Demo-模拟对话框

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .hide{
            display: none;
        }
        .item .header{
            height: 35px;
            background-color: #2459a2;
            color: white;
            line-height: 35px;
        }
    </style>
</head>
<body>
    <div style="height: 48px;"></div>
    <div style=" 300px;">
        <div class="item">
            <div id="i1" class="header" onclick="ChangeMenu('i1');">菜单1</div>
            <div class="content">
                <div>内容1</div>
                <div>内容1</div>
                <div>内容1</div>
            </div>
        </div>
        <div class="item">
            <div id="i2" class="header" onclick="ChangeMenu('i2');">菜单2</div>
            <div class="content hide">
                <div>内容2</div>
                <div>内容2</div>
                <div>内容2</div>
            </div>
        </div>
        <div class="item">
            <div id="i3" class="header" onclick="ChangeMenu('i3');">菜单3</div>
            <div class="content hide">
                <div>内容3</div>
                <div>内容3</div>
                <div>内容3</div>
            </div>
        </div>
        <div class="item">
            <div id="i4" class="header" onclick="ChangeMenu('i4');">菜单4</div>
            <div class="content hide">
                <div>内容4</div>
                <div>内容4</div>
                <div>内容4</div>
            </div>
        </div>
    </div>
 
    <script>
        function ChangeMenu(hid){
            //当前菜单标题div
            var current_header = document.getElementById(hid);
            //获取所有item的数组
            var item_list = current_header.parentElement.parentElement.children;
            for(var i=0;i<item_list.length;i++){
                var current_item = item_list[i];
                //把所有的内容全部隐藏
                current_item.children[1].classList.add("hide");
            }
            //把菜单标题下的隐藏去掉
            current_header.nextElementSibling.classList.remove("hide");
 
        }
    </script>
</body>
</html>

Demo-后台左侧菜单

4、标签操作

4.1、创建标签

// 方式一
var tag = document.createElement('a')
tag.innerText = "wupeiqi"
tag.className = "c1"
tag.href = "http://www.baidu.com"
 
// 方式二
var tag = "<a class='c1' href='http://www.baidu.com'>百度</a>"

4.2、操作标签

// 方式一
var obj = "<input type='text' />";
xxx.insertAdjacentHTML("beforeEnd",obj);
xxx.insertAdjacentElement('afterBegin',document.createElement('p'))
 
//PS：第一个参数只能是'beforeBegin'、 'afterBegin'、 'beforeEnd'、 'afterEnd'
 
// 方式二
var tag = document.createElement('a')
xxx.appendChild(tag)
xxx.insertBefore(tag,xxx[1])

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <input type="button" onclick="AddEle1();" value="+" />
    <input type="button" onclick="AddEle2();" value="+" />
    <div id="i1">
        <p><input type="text" /></p>

    </div>
    <script>
        function AddEle1(){
            // 创建一个标签
            // 将标签添加到i1里面
            var tag = "<p><input type='text'/></p>";
            // 注意：第一个参数只能是'beforeBegin'、 'afterBegin'、 'beforeEnd'、 'afterEnd'
            document.getElementById('i1').insertAdjacentHTML("beforeEnd",tag);
        }
        function AddEle2(){
            // 创建一个标签
            // 将标签添加到i1里面
            var tag = document.createElement('input');
            tag.setAttribute('type', 'text');
            tag.style.fontSize = '16px';
            tag.style.color = 'red';

            var p = document.createElement('p');
            p.appendChild(tag);

            document.getElementById('i1').appendChild(p);
        }
    </script>
</body>
</html>

Demo-新增/减少表格

5、样式操作

var obj = document.getElementById('i1')
 
obj.style.fontSize = "32px";
obj.style.backgroundColor = "red";

6、位置操作

总文档高度
document.documentElement.offsetHeight
  
当前文档占屏幕高度
document.documentElement.clientHeight
  
自身高度
tag.offsetHeight
  
距离上级定位高度
tag.offsetTop
  
父定位标签
tag.offsetParent
  
滚动高度
tag.scrollTop
 
/*
    clientHeight -> 可见区域：height + padding
    clientTop    -> border高度
    offsetHeight -> 可见区域：height + padding + border
    offsetTop    -> 上级定位标签的高度
    scrollHeight -> 全文高：height + padding
    scrollTop    -> 滚动高度
    特别的：
        document.documentElement代指文档根节点
*/

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<body style="margin: 0;">
    <div style="height: 900px;">

    </div>
    <div style="padding: 10px;">
        <div id="i1" style="height:190px;padding: 2px;border: 1px solid red;margin: 8px;">
                <p>asdf</p>
                <p>asdf</p>
                <p>asdf</p>
                <p>asdf</p>
                <p>asdf</p>
        </div>
    </div>

    <script>
        var i1 = document.getElementById('i1');

        console.log(i1.clientHeight); // 可见区域：height + padding
        console.log(i1.clientTop);    // border高度
        console.log('=====');
        console.log(i1.offsetHeight); // 可见区域：height + padding + border
        console.log(i1.offsetTop);    // 上级定位标签的高度
        console.log('=====');
        console.log(i1.scrollHeight);   //全文高：height + padding
        console.log(i1.scrollTop);      // 滚动高度
        console.log('=====');

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

demo

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<style>

    body{
        margin: 0px;
    }
    img {
        border: 0;
    }
    ul{
        padding: 0;
        margin: 0;
        list-style: none;
    }
    .clearfix:after {
        content: ".";
        display: block;
        height: 0;
        clear: both;
        visibility: hidden;
    }

    .wrap{
        width: 980px;
        margin: 0 auto;
    }

    .pg-header{
        background-color: #303a40;
        -webkit-box-shadow: 0 2px 5px rgba(0,0,0,.2);
        -moz-box-shadow: 0 2px 5px rgba(0,0,0,.2);
        box-shadow: 0 2px 5px rgba(0,0,0,.2);
    }
    .pg-header .logo{
        float: left;
        padding:5px 10px 5px 0px;
    }
    .pg-header .logo img{
        vertical-align: middle;
        width: 110px;
        height: 40px;

    }
    .pg-header .nav{
        line-height: 50px;
    }
    .pg-header .nav ul li{
        float: left;
    }
    .pg-header .nav ul li a{
        display: block;
        color: #ccc;
        padding: 0 20px;
        text-decoration: none;
        font-size: 14px;
    }
    .pg-header .nav ul li a:hover{
        color: #fff;
        background-color: #425a66;
    }
    .pg-body{

    }
    .pg-body .catalog{
        position: absolute;
        top:60px;
        width: 200px;
        background-color: #fafafa;
        bottom: 0px;
    }
    .pg-body .catalog.fixed{
        position: fixed;
        top:10px;
    }

    .pg-body .catalog .catalog-item.active{
        color: #fff;
        background-color: #425a66;
    }

    .pg-body .content{
        position: absolute;
        top:60px;
        width: 700px;
        margin-left: 210px;
        background-color: #fafafa;
        overflow: auto;
    }
    .pg-body .content .section{
        height: 500px;
    }
</style>
<body onscroll="ScrollEvent();">
<div class="pg-header">
    <div class="wrap clearfix">
        <div class="logo">
            <a href="#">
                <img src="http://core.pc.lietou-static.com/revs/images/common/logo_7012c4a4.pn">
            </a>
        </div>
        <div class="nav">
            <ul>
                <li>
                    <a  href="#">首页</a>
                </li>
                <li>
                    <a  href="#">功能一</a>
                </li>
                <li>
                    <a  href="#">功能二</a>
                </li>
            </ul>
        </div>

    </div>
</div>
<div class="pg-body">
    <div class="wrap">
        <div class="catalog">
            <div class="catalog-item" auto-to="function1"><a>第1张</a></div>
            <div class="catalog-item" auto-to="function2"><a>第2张</a></div>
            <div class="catalog-item" auto-to="function3"><a>第3张</a></div>
        </div>
        <div class="content">
            <div menu="function1" class="section">
                <h1>第一章</h1>
            </div>
            <div menu="function2" class="section">
                <h1>第二章</h1>
            </div>
            <div menu="function3" class="section">
                <h1>第三章</h1>
            </div>
        </div>
    </div>

</div>
    <script>
        function ScrollEvent(){
            var bodyScrollTop = document.body.scrollTop;
            if(bodyScrollTop>50){
                document.getElementsByClassName('catalog')[0].classList.add('fixed');
            }else{
                document.getElementsByClassName('catalog')[0].classList.remove('fixed');
            }

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

demo-滚动固定

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<style>

    body{
        margin: 0px;
    }
    img {
        border: 0;
    }
    ul{
        padding: 0;
        margin: 0;
        list-style: none;
    }
    h1{
        padding: 0;
        margin: 0;
    }
    .clearfix:after {
        content: ".";
        display: block;
        height: 0;
        clear: both;
        visibility: hidden;
    }

    .wrap{
        width: 980px;
        margin: 0 auto;
    }

    .pg-header{
        background-color: #303a40;
        -webkit-box-shadow: 0 2px 5px rgba(0,0,0,.2);
        -moz-box-shadow: 0 2px 5px rgba(0,0,0,.2);
        box-shadow: 0 2px 5px rgba(0,0,0,.2);
    }
    .pg-header .logo{
        float: left;
        padding:5px 10px 5px 0px;
    }
    .pg-header .logo img{
        vertical-align: middle;
        width: 110px;
        height: 40px;

    }
    .pg-header .nav{
        line-height: 50px;
    }
    .pg-header .nav ul li{
        float: left;
    }
    .pg-header .nav ul li a{
        display: block;
        color: #ccc;
        padding: 0 20px;
        text-decoration: none;
        font-size: 14px;
    }
    .pg-header .nav ul li a:hover{
        color: #fff;
        background-color: #425a66;
    }
    .pg-body{

    }
    .pg-body .catalog{
        position: absolute;
        top:60px;
        width: 200px;
        background-color: #fafafa;
        bottom: 0px;
    }
    .pg-body .catalog.fixed{
        position: fixed;
        top:10px;
    }

    .pg-body .catalog .catalog-item.active{
        color: #fff;
        background-color: #425a66;
    }

    .pg-body .content{
        position: absolute;
        top:60px;
        width: 700px;
        margin-left: 210px;
        background-color: #fafafa;
        overflow: auto;
    }
    .pg-body .content .section{
        height: 500px;
        border: 1px solid red;
    }
</style>
<body onscroll="ScrollEvent();">
<div class="pg-header">
    <div class="wrap clearfix">
        <div class="logo">
            <a href="#">
                <img src="http://core.pc.lietou-static.com/revs/images/common/logo_7012c4a4.pn">
            </a>
        </div>
        <div class="nav">
            <ul>
                <li>
                    <a  href="#">首页</a>
                </li>
                <li>
                    <a  href="#">功能一</a>
                </li>
                <li>
                    <a  href="#">功能二</a>
                </li>
            </ul>
        </div>

    </div>
</div>
<div class="pg-body">
    <div class="wrap">
        <div class="catalog" id="catalog">
            <div class="catalog-item" auto-to="function1"><a>第1张</a></div>
            <div class="catalog-item" auto-to="function2"><a>第2张</a></div>
            <div class="catalog-item" auto-to="function3"><a>第3张</a></div>
        </div>
        <div class="content" id="content">
            <div menu="function1" class="section">
                <h1>第一章</h1>
            </div>
            <div menu="function2" class="section">
                <h1>第二章</h1>
            </div>
            <div menu="function3" class="section">
                <h1>第三章</h1>
            </div>
        </div>
    </div>

</div>
    <script>
        function ScrollEvent(){
            var bodyScrollTop = document.body.scrollTop;
            if(bodyScrollTop>50){
                document.getElementsByClassName('catalog')[0].classList.add('fixed');
            }else{
                document.getElementsByClassName('catalog')[0].classList.remove('fixed');
            }

            var content = document.getElementById('content');
            var sections = content.children;
            for(var i=0;i<sections.length;i++){
                var current_section = sections[i];

                // 当前标签距离顶部绝对高度
                var scOffTop = current_section.offsetTop + 60;

                // 当前标签距离顶部，相对高度
                var offTop = scOffTop - bodyScrollTop;

                // 当前标签高度
                var height = current_section.scrollHeight;

                if(offTop<0 && -offTop < height){
                    // 当前标签添加active
                    // 其他移除 active
                    var menus = document.getElementById('catalog').children;
                    var current_menu = menus[i];
                    current_menu.classList.add('active');
                    for(var j=0;j<menus.length;j++){
                        if(menus[j] == current_menu){

                        }else{
                            menus[j].classList.remove('active');
                        }
                    }
                    break;
                }

            }


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

demo-滚动菜单

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<style>

    body{
        margin: 0px;
    }
    img {
        border: 0;
    }
    ul{
        padding: 0;
        margin: 0;
        list-style: none;
    }
    h1{
        padding: 0;
        margin: 0;
    }
    .clearfix:after {
        content: ".";
        display: block;
        height: 0;
        clear: both;
        visibility: hidden;
    }

    .wrap{
        width: 980px;
        margin: 0 auto;
    }

    .pg-header{
        background-color: #303a40;
        -webkit-box-shadow: 0 2px 5px rgba(0,0,0,.2);
        -moz-box-shadow: 0 2px 5px rgba(0,0,0,.2);
        box-shadow: 0 2px 5px rgba(0,0,0,.2);
    }
    .pg-header .logo{
        float: left;
        padding:5px 10px 5px 0px;
    }
    .pg-header .logo img{
        vertical-align: middle;
        width: 110px;
        height: 40px;

    }
    .pg-header .nav{
        line-height: 50px;
    }
    .pg-header .nav ul li{
        float: left;
    }
    .pg-header .nav ul li a{
        display: block;
        color: #ccc;
        padding: 0 20px;
        text-decoration: none;
        font-size: 14px;
    }
    .pg-header .nav ul li a:hover{
        color: #fff;
        background-color: #425a66;
    }
    .pg-body{

    }
    .pg-body .catalog{
        position: absolute;
        top:60px;
        width: 200px;
        background-color: #fafafa;
        bottom: 0px;
    }
    .pg-body .catalog.fixed{
        position: fixed;
        top:10px;
    }

    .pg-body .catalog .catalog-item.active{
        color: #fff;
        background-color: #425a66;
    }

    .pg-body .content{
        position: absolute;
        top:60px;
        width: 700px;
        margin-left: 210px;
        background-color: #fafafa;
        overflow: auto;
    }
    .pg-body .content .section{
        height: 500px;
        border: 1px solid red;
    }
</style>
<body onscroll="ScrollEvent();">
<div class="pg-header">
    <div class="wrap clearfix">
        <div class="logo">
            <a href="#">
                <img src="http://core.pc.lietou-static.com/revs/images/common/logo_7012c4a4.pn">
            </a>
        </div>
        <div class="nav">
            <ul>
                <li>
                    <a  href="#">首页</a>
                </li>
                <li>
                    <a  href="#">功能一</a>
                </li>
                <li>
                    <a  href="#">功能二</a>
                </li>
            </ul>
        </div>

    </div>
</div>
<div class="pg-body">
    <div class="wrap">
        <div class="catalog" id="catalog">
            <div class="catalog-item" auto-to="function1"><a>第1张</a></div>
            <div class="catalog-item" auto-to="function2"><a>第2张</a></div>
            <div class="catalog-item" auto-to="function3"><a>第3张</a></div>
        </div>
        <div class="content" id="content">
            <div menu="function1" class="section">
                <h1>第一章</h1>
            </div>
            <div menu="function2" class="section">
                <h1>第二章</h1>
            </div>
            <div menu="function3" class="section">
                <h1>第三章</h1>
            </div>
        </div>
    </div>

</div>
    <script>
        function ScrollEvent(){
            var bodyScrollTop = document.body.scrollTop;
            if(bodyScrollTop>50){
                document.getElementsByClassName('catalog')[0].classList.add('fixed');
            }else{
                document.getElementsByClassName('catalog')[0].classList.remove('fixed');
            }

            var content = document.getElementById('content');
            var sections = content.children;
            for(var i=0;i<sections.length;i++){
                var current_section = sections[i];

                // 当前标签距离顶部绝对高度
                var scOffTop = current_section.offsetTop + 60;

                // 当前标签距离顶部，相对高度
                var offTop = scOffTop - bodyScrollTop;

                // 当前标签高度
                var height = current_section.scrollHeight;

                if(offTop<0 && -offTop < height){
                    // 当前标签添加active
                    // 其他移除 active
                    var menus = document.getElementById('catalog').children;
                    var current_menu = menus[i];
                    current_menu.classList.add('active');
                    for(var j=0;j<menus.length;j++){
                        if(menus[j] == current_menu){

                        }else{
                            menus[j].classList.remove('active');
                        }
                    }
                    break;
                }

            }


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

demo-滚动高度

7、提交表单

document.geElementById('form').submit()

8、其他操作

console.log                 输出框
alert                       弹出框
confirm                     确认框
  
// URL和刷新
location.href               获取当前URL
location.href = "url"       重定向（赋值一个新的url）
location.reload()           重新加载(刷新 相当于location.herf=location.herf)
  
// 定时器
setInterval                 多次定时器
clearInterval               清除多次定时器
setTimeout                  单次定时器
clearTimeout                清除单次定时器

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <form id="f1" action="http://www.baidu.com">
        <input type="text" />
        <input type="submit" value="提交" />
        <a onclick="submitForm();">提交吧</a>
    </form>

    <script>
        function submitForm(){
            //document.getElementById('f1').submit()
            //alert(123);
            var v = confirm('真的要删除吗？');
            console.log(v);
        }

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

Demo-确认框

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <script>
        // 定时器，一直执行
        var obj = setInterval(function(){
            console.log(1);
       //可设置条件语句进行清除定时器
            clearInterval(obj);
        }, 1000);

        // 定时器，只执行一次（到时间自动清除定时器，也可手动清除）
        setTimeout(function () {
            console.log('timeout');
        },15000);

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

Demo-定时器

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <div id="status"></div>

    <input type="button" value="删除" onclick="DeleteEle();" />

    <script>
        function  DeleteEle(){
            document.getElementById('status').innerText = "已删除";
            setTimeout(function () {
                    document.getElementById('status').innerText = "";
            }, 50000);
        }
    </script>
</body>
</html>

Demo-单次定时器清除文本

三、事件

1、绑定事件两种方式：

a. 直接标签绑定 onclick='xxx()' onfocus
b. 先获取Dom对象，然后进行绑定document.getElementById('xx').onclick（document.getElementById('xx').onfocus）

2、this，当前触发事件的标签

a. 第一种绑定触发方式

<input id='i1' type='button' onclick='ClickOn(this)'>
function ClickOn(self){
// self 当前点击的标签
}

b. 第二种绑定触发方式

<input id='i1' type='button' >
document.getElementById('i1').onclick = function(){
           // this 代指当前点击的标签
}

c.第三种绑定触发方式

//element.addEventListener(event, function, useCapture)
//event，指定事件名（字符串格式，不要使用 "on" 前缀。 例如，使用 "click" ,而不是使用 "onclick"） 
//function,指定要事件触发时执行的函数。 
//useCapture,布尔值，指定事件是否在捕获或冒泡阶段执行
mymain.addEventListener("click",function({console.log("main")},true);

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<style>
    #main{
        background-color: red;
        300px;
        height:400px;
    }
    #content{
        background-color: pink;
        150px;
        height:200px;
    }
</style>
<body>
    <div id="main">
        <div id="content"></div>
    </div>

    <script>

        var mymain = document.getElementById("main");
        var mycontent = document.getElementById("content");
        mymain.addEventListener("click",function(){console.log("main")},true); //Ture是捕获模式，先点击的标签就会被先被捕获到，从而展示出来，   False是冒泡模式，最低层绑定的事件先冒出来从而展示
        mycontent.addEventListener("click",function(){console.log("content")},true);
    </script>


</body>
</html>

Demo-捕获/冒泡示例

3、对于事件需要注意的要点：

this
event
事件链以及跳出

this标签当前正在操作的标签，event封装了当前事件的内容。

4、dom的demo示例：

<!DOCTYPE html>
<html>
    <head>
        <meta charset='utf-8' />
        <title></title>
        
        <style>
            .gray{
                color:gray;
            }
            .black{
                color:black;
            }
        </style>
        <script type="text/javascript">
            function Enter(){
               var id= document.getElementById("tip")
               id.className = 'black';
               if(id.value=='请输入关键字'||id.value.trim()==''){
                    id.value = ''
               }
            }
            function Leave(){
                var id= document.getElementById("tip")
                var val = id.value;
                if(val.length==0||id.value.trim()==''){
                    id.value = '请输入关键字'
                    id.className = 'gray';
                }else{
                    id.className = 'black';
                }
            }
        </script>
    </head>
    <body>
        <input type='text' class='gray' id='tip' value='请输入关键字' onfocus='Enter();'  onblur='Leave();'/>
    </body>
</html>

Demo-搜索框

<!DOCTYPE html>
<html>
    <head>
        <meta charset='utf-8' >
        <title>欢迎上级单位莅临指导&nbsp;&nbsp;</title>
        <script type='text/javascript'>
            function Go(){
                var content = document.title;
                var firstChar = content.charAt(0)
                var sub = content.substring(1,content.length)
                document.title = sub + firstChar;
            }
            setInterval('Go()',1000);
        </script>
    </head>
    <body>    
    </body>
</html>

Demo-跑马灯

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<style>

</style>
<body>

<table border="1" width="300px">
    <tr onmouseover="t1(0);" onmouseout="t2(0);"><td>1</td><td>2</td><td>2</td></tr>
    <tr onmouseover="t1(1);" onmouseout="t2(1);"><td>1</td><td>2</td><td>2</td></tr>
    <tr onmouseover="t1(2);" onmouseout="t2(2);"><td>1</td><td>2</td><td>2</td></tr>
</table>
    <script>
        function t1(n){
            var myTrs = document.getElementsByTagName("tr")[n];
//            console.log(myTrs);
            myTrs.style.backgroundColor = "red";
        }

        function t2(n){
            var myTrs = document.getElementsByTagName("tr")[n];
            myTrs.style.backgroundColor = "";
        }
    </script>


</body>
</html>

Demo-onmouseover+onmouseout表格换色

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<style>

</style>
<body>

<table id="i1" border="1" width="300px">
    <tr><td>1</td><td>2</td><td>2</td></tr>
    <tr><td>1</td><td>2</td><td>2</td></tr>
    <tr><td>1</td><td>2</td><td>2</td></tr>
</table>

<table id='i2' border="1" width="300px">
    <tr><td>1</td><td>2</td><td>2</td></tr>
    <tr><td>1</td><td>2</td><td>2</td></tr>
    <tr><td>1</td><td>2</td><td>2</td></tr>
</table>
    <script>
        var myTrs = document.getElementsByTagName("tr");
        var len = myTrs.length;
        for(var i=0;i<len;i++){
            // i=0,i=1,i=2
            myTrs[i].onmouseover = function(){
                 this.style.backgroundColor = "red"; //这里不能写成myTrs[i],因为JavaScript作用域的关系，在for循环的时候i=0,i=1,i=2，这个时候function还在内存中没有编译运行
            };

            myTrs[i].onmouseout = function(){
             this.style.backgroundColor = "";
             }
        }
    </script>


</body>
</html>

Demo-表格换色之（行为、样式、结构相分离版）

更多更详细DOM资料：点击