八、Vue事件修饰符的使用
在程序开发中，有时候需要阻止具有默认事件的标签，如submit标签默认会提交，一般使用会event.preventDefault()阻止默认事件行为。下面通过冒泡事件的案例来演示。
<span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important"></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span class="cm-tag cm-bracket" style="box-sizing: border-box"><</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">html</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span class="cm-tag cm-bracket" style="box-sizing: border-box"><</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">head</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span class="cm-tag cm-bracket" style="box-sizing: border-box"><</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">title</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span>事件修饰符<span class="cm-tag cm-bracket" style="box-sizing: border-box"></</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">title</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span class="cm-tag cm-bracket" style="box-sizing: border-box"><</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">meta</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">charset</span>=<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">"utf-8"</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span class="cm-tag cm-bracket" style="box-sizing: border-box"><</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">script</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">src</span>=<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">"https://cdn.jsdelivr.net/npm/vue@2.5.21/dist/vue.js"</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">script</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span class="cm-tag cm-bracket" style="box-sizing: border-box"><</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">style</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(232, 191, 106) !important">#parent</span> {</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">width</span>: <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">100px</span>;</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">height</span>: <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">100px</span>;</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">background</span>: <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">pink</span>;</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> }</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(232, 191, 106) !important">#child</span> {</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">width</span>: <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">50px</span>;</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">height</span>: <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">50px</span>;</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">background</span>: <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">yellow</span>;</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> }</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span class="cm-tag cm-bracket" style="box-sizing: border-box"></</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">style</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span class="cm-tag cm-bracket" style="box-sizing: border-box"></</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">head</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span class="cm-tag cm-bracket" style="box-sizing: border-box"><</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">body</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span class="cm-tag cm-bracket" style="box-sizing: border-box"><</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">div</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">id</span>=<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">"app"</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span class="cm-tag cm-bracket" style="box-sizing: border-box"><</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">div</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">id</span>=<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">"parent"</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">v-on:click</span>=<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">"parentMethod"</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> 父元素</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span class="cm-tag cm-bracket" style="box-sizing: border-box"><</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">div</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">id</span>=<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">"child"</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">v-on:click.stop</span>=<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">"childMethod"</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> 子元素</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span class="cm-tag cm-bracket" style="box-sizing: border-box"></</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">div</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span class="cm-tag cm-bracket" style="box-sizing: border-box"></</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">div</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(98, 151, 85) !important"><!--阻止a标签跳转--></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span class="cm-tag cm-bracket" style="box-sizing: border-box"><</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">a</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">v-on:click.prevent</span>=<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">"doThat"</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">href</span>=<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">"https://www.ziruchu.com"</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span>12313213<span class="cm-tag cm-bracket" style="box-sizing: border-box"></</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">a</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span class="cm-tag cm-bracket" style="box-sizing: border-box"></</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">div</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box"></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span class="cm-tag cm-bracket" style="box-sizing: border-box"><</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">script</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">var</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">app</span> <span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">=</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">new</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Vue</span>({</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">el</span>: <span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">"#app"</span>,</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">data</span>: {</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">count</span>:<span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">0</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> },</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">methods</span>:{</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">parentMethod</span> () {</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">console</span>.<span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">log</span>(<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">'parent'</span>);</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> },</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">childMethod</span> () {</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">console</span>.<span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">log</span>(<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">'child'</span>);</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> },</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">doThat</span>(){</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">console</span>.<span style="box-sizing: border-box;color: rgb(97, 175, 239) !important">log</span>(<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">'干嘛，不让你跳转~~~'</span>)</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> }</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> }</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box"></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> });</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> <span class="cm-tag cm-bracket" style="box-sizing: border-box"></</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">script</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box"></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span class="cm-tag cm-bracket" style="box-sizing: border-box"></</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">body</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span class="cm-tag cm-bracket" style="box-sizing: border-box"></</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">html</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span>
什么是事件冒泡？
用个栗子来说明，把一颗石子扔向池塘，会产生很多气泡，这些气泡由里到外不断的冒泡，这些气泡由小到大扩散着。
在这个栗子中，默认使用的是事件冒泡。
1）当在parent区域点击时，只会输出 parent。事件并没有传递到子区域；
2）当在child区域点击时，首先会输出 child，然后再输出 parent
从这里可以发现，点击child区域时，事件parent事件也被触发了。当点击子区域时，要阻止parent执行，怎么办？Vue提供了事件修饰符。下面对代码进行小的改动。
<span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span class="cm-tag cm-bracket" style="box-sizing: border-box"><</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">div</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">id</span>=<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">"child"</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">v-on:click.stop</span>=<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">"childMethod"</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"> 子元素</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span class="cm-tag cm-bracket" style="box-sizing: border-box"></</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">div</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span>
在子元素中使用相应的stop事件修饰符就阻止了事件的冒泡，现在再点击child区域是，只会输出 child了。关于事件修饰符有很多，详情参考官方文档，这里只记录一点点。如案例中，阻止a标签默认事件。
事件修饰符
<span style="color: rgb(40, 44, 52); word-spacing: 0.05rem; font-weight: 600; font-family: 宋体, "Times New Roman", Times, Georgia, serif; font-size: 14px; orphans: 4; text-align: justify; white-space: pre-wrap;">
Vue允许为v-on监听键盘事件时为其添加修饰符，我们很难记住keyCode，那么最容易的方法就是别名了。如案例，使用回车键即可触发提交。按键修饰符
<span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span class="cm-tag cm-bracket" style="box-sizing: border-box"><</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">input</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">@keyup.enter</span>=<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">"submit"</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span class="cm-tag cm-bracket" style="box-sizing: border-box"><</span><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">input</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">v-on:keyup.13</span>=<span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">"submit"</span><span class="cm-tag cm-bracket" style="box-sizing: border-box">></span></span>
按键修饰符有：
我是小白，期待和优秀的你一起同行!
小白
2020年12月02日
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