vue计算属性computed实现表单的全选和全不选

说明： 页面使用BootStrap框架搭建

<div id="app">
      <div class="panel panel-info">
        <div class="panel-heading">
          <h3 class="panel-title">全选和反选</h3>
        </div>
        <div class="panel-body">
          <div class="checkbox">
            <label>
              <input type="checkbox" v-model="chkAll" />
              全选
            </label>
          </div>

          <ul class="list-group">
            <li class="list-group-item" 
v-for="(item) in list" :key="item.id">
              <div class="checkbox">
                <label>
                  <input type="checkbox" v-model="item.checked" />
                  {{item.name}}
                </label>
              </div>
            </li>
          </ul>
        </div>
      </div>
    </div>
    <script src="./libs/vue.js"></script>
    <script>
      new Vue({
        el: "#app",
        data: {
          list: [
            {
              id: 1,
              name: "胡一菲",
              checked: false,
            },
            {
              id: 2,
              name: "诺澜",
              checked: false,
            },
            {
              id: 3,
              name: "曾小贤",
              checked: false,
            },
            {
              id: 4,
              name: "张益达",
              checked: false,  //默认不选中
            },
            {
              id: 5,
              name: "诸葛大力",
              checked: true,   //默认选中
            },
          ],
        },
        // computed计算属性：依赖的数据项改变之后进行重新计算
        //  应用场景：数据改变之后会影响某一项结果
        computed: {
          chkAll: {
            // 设置值,当点击全选按钮的时候触发
            set(v) {
              this.list.forEach((item) => (item.checked = v));
            },
            // 取值,当列表中的选择改变之后触发
            get() {
              return (
                this.list.length ===
                this.list.filter((item) => item.checked).length
              );
            },
          },
        },
      });
    </script>

实现效果：