element-ui vue input输入框自动获取焦点聚焦方式

 directives: {
   focus: {
      inserted: function(el) {
        el.querySelector("input").focus();
      }
    }
 },

<el-input
   ...
  v-focus
>
</el-input>

<el-input
  ref="saveTagInput"
 >

this.$refs.saveTagInput.focus();

<template>
  <div class="focusDemo">
    <input type="text" v-model="username" id='inputId'/>
  </div>
</template>
<script>
export default {
  data () {
    return {
      username: ''
    }
  },
  mounted () {
    document.getElementById('inputId').focus()
  }
}
</script>

<template>
  <div class="focusDemo">
    <input ref="inputName" type="text" v-model="username" />
  </div>
</template>
<script>
export default {
  data () {
    return {
      username: ''
    }
  },
  mounted () {
    this.$nextTick(() => {
      this.$refs.inputName.focus()
    })
  }
}
</script>

// 注册一个全局自定义指令 `v-focus`
Vue.directive('focus', {
  // 当被绑定的元素插入到 DOM 中时
  inserted: function (el) {
    // 聚焦元素
    el.focus()
  },
  update: function (el) {
    // 聚焦元素
    el.focus()
  }
})

<template>
  <div class="focusDemo">
    <input type="text" v-model="username" v-focus />
  </div>
</template>
<script>
export default {
  data () {
    return {
      username: ''
    }
  }
}
</script>