Vue.js自定义指令学习使用详解

自定义指令

自定义指令的注册方法和组件很像，也分全局注册和局部注册，比如注册一个v-focus指令用于在、元素初始化时自动获得焦点，共有两种写法：</p> <pre class="brush:js;"> //全局注册 Vue.directive('focus',{ //指令选项 }); //局部注册 var app = new Vue({ el: '#app', directive: { focus: { //指令选项 } } });</pre> <p>自定义指令的选项是由几个钩子函数组成的，每个都是可选的。</p> <p>自定义指令的各个选项如下：</p> <ul> <li><strong>bind：</strong> 只调用一次，指令第一次绑定到元素时调用，用这个钩子函数可以定义一个在绑定时执行一次的初始化动作。</li> <li><strong>inserted：</strong> 被绑定元素插入父节点时调用（父节点存在即可调用，不必在于document中）。</li> <li><strong>update：</strong> 被绑定元素所在的模板更新时调用，而不论绑定值是否变化。通过比较更新前后的绑定值，可以忽略不必要的模板更新。</li> <li><strong>componentUpdated： </strong>被绑定元素所在模板完成一次更新周期时调用。</li> <li><strong>unbind： </strong>只调用一次，指令与元素解绑时调用。<br /> </li> </ul> <p>可以根据需求在不同的钩子函数内完成逻辑代码，例如上面的v-focus，我们希望在元素插入父节点时就调用，那用到的最好是inserted。</p> <pre class="brush:xhtml;"> <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>自定义指令</title> </head> <body> <input type="text" v-focus> </body> </html></pre> <p></p> <p>每个钩子函数都有几个参数可用，具体如下：</p> <ul> <li><strong>el： </strong>指令所绑定的元素，可以用来直接操作DOM<br /> </li> </ul> <ul> <li><strong>binding：</strong> 一个对象，包含以下属性：<br /> </li> </ul> <p> name：指令名，不包括v-前缀<br /> valule：指令的绑定值，例如v-my-directive=“1 + 1”，value的值是2<br /> oldValue：指令绑定的前一个值，仅在update和componentUpdated钩子中可用。无论值是否改变都可用<br /> expression：绑定值的字符串形式。例如v-my-directive=“1 + 1”，expression的值是”1 + 1“<br /> arg：传给指令的参数。例如v-my-directive:foo，arg的值是foo<br /> modifiers：一个包含修饰符的对象。例如v-my-directive.foo.bar，修饰符对象modifiers的值是{ foo:true, bar:true}<br /> </p> <ul> <li><strong>vnode：</strong> Vue编译生成的虚拟节点。<br /> </li> </ul> <ul> <li><strong>oldVnode： </strong>上一个虚拟节点仅在update和componentUpdated钩子中可用。<br /> </li> </ul> <p>示例：</p> <pre class="brush:xhtml;"> <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>自定义指令</title> </head> <body> </body> </html></pre> <p></p> <p>更多教程点击《Vue.js前端组件学习教程》，欢迎大家学习阅读。</p> <p>关于vue.js组件的教程，请大家点击专题vue.js组件学习教程进行学习。</p> <p>以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持考高分网。</p></div> </div> <div style="clear: both;"></div> <div class="author-info fl"> <div><span class="gray">转载请注明：</span>文章转载自 <a href="https://www.mshxw.com/" class="blue">www.mshxw.com</a></div> <div><span class="gray">本文地址：</span><a href="https://www.mshxw.com/it/73012.html" class="blue">https://www.mshxw.com/it/73012.html</a></div> </div> <div class="prev fl"> <p> <a style='text-align:left;' class='center-block text-center glyphicon glyphicon-collapse-down' href="https://www.mshxw.com/it/73051.html">上一篇 JavaScript闭包相关知识解析</a> </p> <p> <a style='text-align:left;' class='center-block text-center glyphicon glyphicon-collapse-down' href="https://www.mshxw.com/it/73013.html">下一篇细述Javascript的加法运算符的具体使用</a> </p> </div> <div class="new_tag fl"> </div> </div> <div class="new_r fr" style="border-radius:10px;"> <div class="tui fl"> 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