<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.2.1/vue.min.js"></script>

<div id="app">

  <div @click="layerShow = !layerShow">

    点击打开lyaer

  </div>

  <div class="layer-wrap" v-if="layerShow" @click="layerShow = !layerShow">

    </div>

</div>

new Vue({

  el:'#app',

  data:{

    layerShow:false

  }

})

.layer-wrap{

  position:fixed;

  top:0;

  left:0;

  right:0;

  bottom:0;

  background:rgba(0,0,0,0.4)

}