jsweb2 - 技术栈

事件监听：程序检测是否有事件产生，一旦有事件触发，就立即调用一个函数做出响应

语法：元素对象.addEventListener('事件类型',要执行的函数)

```html

const btn = document.querySelector('.btn')

btn.addEventListener('click',function(){

alert('点击l')

})

</script>

```

举例:按钮广告事件

html 复制代码

    <style>

        .adv{

            background-color: brown;

            position: relative;

            top:100px;

            left:500px;

            text-align: center;

        }

        img{

            width: 500px;

        }

        #close{

            width: 20px;

            height: 20px;

            background-color: white;

            position: absolute;

            top:10px;

            right:10px;

            cursor:pointer;

        }

        .hide{

            display: none;

        }

        .show{

            display: inline-block;

        }

    </style>

<body>

    <p>真传奇，和渣渣辉一起一刀999</p>

    <button id="btn">马上下载</button>

    <!-- 广告 -->

    <div id="adv" class="adv hide">

        <div id="close">X</div>

        <img src="../images/slider01.jpg" alt=""><br/>

        <h3>双十一跳楼大甩卖</h3>

    </div>

    <!-- 游戏注册 -->

    <div class="register hide">

        <h1>用户注册</h1>

        <form action="">

            输入手机号：<input type="text" name="uname"><button class="btn">提交</button>

        </form>

    </div>  

    <script>

        const bt = document.querySelector('#btn')

        const xx = document.querySelector('#close')

        const adv = document.querySelector('.adv')

        const register=document.querySelector('.register')

        bt.addEventListener('click',function(){

            adv.classList.remove('hide')

            adv.classList.add('show')

        })

        xx.addEventListener('click',function(){

            adv.classList.remove('show')

            adv.classList.add('hide')

            register.classList.remove('hide')

            register.classList.add('show')

        })

    </script>

事件类型

鼠标事件（鼠标触发）
click 鼠标点击
mouseenter 鼠标经过
mouseleave 鼠标离开

随机点名

html 复制代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .suiji{
            width: 300px;
            height: 150px;
            background-color: rgb(255, 255, 255);
            margin: 0 auto;
            font-size: 20px;
            font-weight: bold;
            /* text-align: center; */
        }
        h2{
            text-align: center;
        }
        button{
            width: 80px;
            height: 30px;
        }
        .btn{
            text-align: center;
        }
    </style>
</head>
<body>
    <div class="suiji">
        <h2>随机点名</h2>
        <p>问题是：<span>这里显示人名</span></p>
        <div class="btn">
            <button id="action">开始</button>
            <button id="over">结束</button>
        </div>
    </div>
    <script>
        const name=['张三','李四','王五','赵六','小七','老八','九九']
        // 获取
        const sp=document.querySelector('span')
        const action=document.querySelector('#action')
        const over=document.querySelector('#over')
        let time=0
        let num=0
        // 点击开始按钮
        action.addEventListener('click',function(){
            time=setInterval(function(){
                num=Math.floor(Math.random()*name.length)
                sp.innerHTML=name[num]  
            },100)     
            if (name.length===1) {
                action.disabled=true
                over.disabled=true
            }
        })
        // 点击结束按钮
        over.addEventListener('click',function(){
                clearInterval(time)
                name.splice(num,1)
                // console.log(name)   打印删除后的名单数组
            })
        
        
    </script>
</body>
</html>