[рони]

fori,

<script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>

<div id="vue">
  <button @click="foc">show+focus</button>
  <input type="text" id="ob" v-show="show" ref="test">
</div>
<script>

var vue = new Vue({
  el: '#vue',
  data: {
      show:false,
  },
  methods: {
   foc(){
       (vue.show=!vue.show) && this.$nextTick(() => this.setFocus());
    },
   setFocus() {
        this.$refs.test.focus();
    }
  }
})
</script>