1. 事件修饰符
Vue中的事件修饰符：
- prevent：阻止默认事件（常用）；
- stop：阻止事件冒泡（常用）；
- once：事件只触发一次（常用）；
- capture：使用事件的捕获模式；
- self：只有event.target是当前操作的元素时才触发事件；
示例代码:
html
<!DOCTYPE html>
<html><head>
<meta charset="UTF-8" />
<title>事件修饰符</title>
<!-- 引入Vue -->
<script type="text/javascript" src=".../js/vue.js"></script>
<style>
* {
margin-top: 20px;
}
<span class="token selector">.demo1</span> <span class="token punctuation">{<!-- --></span>
<span class="token property">height</span><span class="token punctuation">:</span> 50px<span class="token punctuation">;</span>
<span class="token property">background-color</span><span class="token punctuation">:</span> skyblue<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token selector">.box1</span> <span class="token punctuation">{<!-- --></span>
<span class="token property">padding</span><span class="token punctuation">:</span> 5px<span class="token punctuation">;</span>
<span class="token property">background-color</span><span class="token punctuation">:</span> skyblue<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token selector">.box2</span> <span class="token punctuation">{<!-- --></span>
<span class="token property">padding</span><span class="token punctuation">:</span> 5px<span class="token punctuation">;</span>
<span class="token property">background-color</span><span class="token punctuation">:</span> orange<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token selector">.list</span> <span class="token punctuation">{<!-- --></span>
<span class="token property">width</span><span class="token punctuation">:</span> 200px<span class="token punctuation">;</span>
<span class="token property">height</span><span class="token punctuation">:</span> 200px<span class="token punctuation">;</span>
<span class="token property">background-color</span><span class="token punctuation">:</span> peru<span class="token punctuation">;</span>
<span class="token property">overflow</span><span class="token punctuation">:</span> auto<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token selector">li</span> <span class="token punctuation">{<!-- --></span>
<span class="token property">height</span><span class="token punctuation">:</span> 100px<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</span></span><span class="token tag"><span class="token tag"><span class="token punctuation"></</span>style</span><span class="token punctuation">></span></span>
</head>
<body>
<!--
Vue中的事件修饰符：
1.prevent：阻止默认事件（常用）；
2.stop：阻止事件冒泡（常用）；
3.once：事件只触发一次（常用）；
4.capture：使用事件的捕获模式；
5.self：只有event.target是当前操作的元素时才触发事件；
-->
<!-- 准备好一个容器-->
<div id="root">
<h2>欢迎来到{ {name}}学习</h2>
<!-- 阻止默认事件（常用） -->
<a href="http://www.atguigu.com" @click.prevent="showInfo">点我提示信息</a>
<span class="token comment"><!-- 阻止事件冒泡（常用） --></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>div</span> <span class="token attr-name">class</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>demo1<span class="token punctuation">"</span></span> <span class="token attr-name">@click</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>showInfo<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>button</span> <span class="token attr-name">@click.stop</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>showInfo<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>点我提示信息<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>button</span><span class="token punctuation">></span></span>
<span class="token comment"><!-- 修饰符可以连续写 先写的先起作用: 这样写就是先阻止默认行为后阻止冒泡--></span>
<span class="token comment"><!-- <a href="http://www.atguigu.com" @click.prevent.stop="showInfo">点我提示信息</a> --></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>div</span><span class="token punctuation">></span></span>
<span class="token comment"><!-- 事件只触发一次（常用） --></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>button</span> <span class="token attr-name">@click.once</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>showInfo<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>点我提示信息<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>button</span><span class="token punctuation">></span></span>
<span class="token comment"><!-- 使用事件的捕获模式 --></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>div</span> <span class="token attr-name">class</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>box1<span class="token punctuation">"</span></span> <span class="token attr-name">@click.capture</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>showMsg(1)<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>
div1
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>div</span> <span class="token attr-name">class</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>box2<span class="token punctuation">"</span></span> <span class="token attr-name">@click</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>showMsg(2)<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>
div2
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>div</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>div</span><span class="token punctuation">></span></span>
<span class="token comment"><!-- 只有event.target是当前操作的元素时才触发事件； --></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>div</span> <span class="token attr-name">class</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>demo1<span class="token punctuation">"</span></span> <span class="token attr-name">@click.self</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>showInfo<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>button</span> <span class="token attr-name">@click</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>showInfo<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>点我提示信息<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>button</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>div</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>div</span><span class="token punctuation">></span></span>
</body>
<script type="text/javascript">
Vue.config.productionTip = false //阻止 vue 在启动时生成生产提示。
<span class="token keyword">new</span> <span class="token class-name">Vue</span><span class="token punctuation">(</span><span class="token punctuation">{<!-- --></span>
<span class="token literal-property property">el</span><span class="token operator">:</span> <span class="token string">'#root'</span><span class="token punctuation">,</span>
<span class="token literal-property property">data</span><span class="token operator">:</span> <span class="token punctuation">{<!-- --></span>
<span class="token literal-property property">name</span><span class="token operator">:</span> <span class="token string">'尚硅谷'</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
<span class="token literal-property property">methods</span><span class="token operator">:</span> <span class="token punctuation">{<!-- --></span>
<span class="token function">showInfo</span><span class="token punctuation">(</span><span class="token parameter">e</span><span class="token punctuation">)</span> <span class="token punctuation">{<!-- --></span>
<span class="token function">alert</span><span class="token punctuation">(</span><span class="token string">'同学你好！'</span><span class="token punctuation">)</span>
<span class="token comment">// console.log(e.target)</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
<span class="token function">showMsg</span><span class="token punctuation">(</span><span class="token parameter">msg</span><span class="token punctuation">)</span> <span class="token punctuation">{<!-- --></span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>msg<span class="token punctuation">)</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>
</script>
</html>
1.1 prevent：阻止默认事件（常用）
html:
html
<!-- 阻止默认事件（常用） -->
<a href="http://www.atguigu.com" @click.prevent="showInfo">点我提示信息</a>js:
运行效果:
a标签的默认有跳转到href的行为，我们把默认行为禁用后，就不会跳转页面
补充:
如果不使用Vue指令，那么怎么屏蔽事件的默认行为呢？
1.2 stop：阻止事件冒泡（常用）
html:
html
<!-- 阻止事件冒泡（常用） -->
<div class="demo1" @click="showInfo">
<button @click.stop="showInfo">点我提示信息</button>
<!-- 修饰符可以连续写 -->
<!-- <a href="http://www.atguigu.com" @click.prevent.stop="showInfo">点我提示信息</a> -->
</div>js:
运行结果:
如果不组织事件冒泡:
如果不使用Vue指令，那么怎么阻止事件冒泡呢？
1.3 once：事件只触发一次（常用）
html:
html
<!-- 事件只触发一次（常用） -->
<button @click.once="showInfo">点我提示信息</button>js:
运行结果:
1.4 capture：使用事件的捕获模式
html:
html
<!-- 使用事件的捕获模式 -->
<div class="box1" @click.capture="showMsg(1)">
div1
<div class="box2" @click="showMsg(2)">
div2
</div>
</div>js:
运行结果:
关闭事件捕获:
分析原因:
1.5 self：只有event.target是当前操作的元素时才触发事件
html:
html
<!-- 只有event.target是当前操作的元素时才触发事件； -->
<div class="demo1" @click.self="showInfo">
<button @click="showInfo">点我提示信息</button>
</div>js:
运行结果:
因为event.target不是当前操作的元素，所有没有触发事件，这个在一定程度上面也可以阻止冒泡
如果不加指令会怎么样？
发生了事件冒泡
