指令与事件方法

指令系统

指令系统就是通过自定义属性实现的一套功能，也是声明式编程的体现。通常在标签上添加 v-* 字样，常见的指令有：

v-bind -> 操作标签属性，可通过: 简写
v-on-> 操作事件，可通过 @ 简写

通过 methods 选项 API 实现添加事件方法，并且 Vue 框架已经帮事件传参机制处理好了

html

<!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>
    <script src="/vue.global.js"></script>
  </head>
  <body>
    <div id="app">
      <div title="{{ message }}">aaaaa</div>
      <div v-bind:title="message" v-bind:class="myClass" v-on:click=" message = 'hi vue' ">aaaaa</div>

      <div :title="message" v-bind:class="myClass" @click=" message = 'hi vue' ">aaaaa</div>
    </div>
    <script>
      let vm = Vue.createApp({
        data() {
          return {
            message: "hello world",
            myClass: "box"
          }
        }
      }).mount("#app")
    </script>
  </body>
</html>

事件方法和传参处理

html

<!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>
    <script src="/vue.global.js"></script>
  </head>
  <body>
    <div id="app">
      <div :title="message" v-bind:class="myClass" @click="handleClick($event, 123)">aaaaa</div>
      {{ message }}
    </div>
    <script>
      let vm = Vue.createApp({
        data() {
          return {
            message: "hello world",
            myClass: "box"
          }
        },
        methods: {
          handleClick(event, num) {
            this.message = "hi vue"
            console.log(event) // 事件对象
            console.log(num) // 123
          }
        }
      }).mount("#app")
    </script>
  </body>
</html>