Javascript如何阻止事件冒泡和事件本身发生-木庄网络博客

本文摘自PHP中文网，作者逆旅行人，侵删。

在Javascript中事件冒泡是由节点产生，然后会影响到父节点，逐级上升，最后慢慢影响到整个页面，但是有时我们想要阻止事件冒泡的发生甚至事件本身的发生呢？本文就带大家一起来了解一下。

1.阻止事件冒泡发生

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .boxA {
            overflow: hidden;
            width: 300px;
            height: 300px;
            margin: 100px auto;
            background-color: blue;
            text-align: center;
        }       
        .boxB {
            width: 200px;
            height: 200px;
            margin: 50px;
            background-color: green;
            line-height: 200px;
            color: #fff;
        }
    </style>
</head>
 
<body>
    <div class="boxA">
        <div class="boxB">boxB</div>
    </div>
    <script>
        var boxA = document.querySelector('.boxA');
        var boxB = document.querySelector('.boxB');
        boxA.onclick = function (e) {
        console.log('我被点击了boxA');
    };
    boxB.onclick = function (e) {
        e.cancelBubble=true; //不冒泡
        console.log('我被点击了boxB');
    };
    </script>
</body>
</html>

2.阻止事件本身发生

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<form action="http://www.php.cn" method="POST">
<button type="submit">按钮1</button>
</form>    
<body>
    <script>
        const btn=document.querySelector("button");
        console.log(btn);
        btn.addEventListener("click",function(e){
            e.preventDefault();
        });
    </script>
</body>
</html>