vue中，点击按钮后，页面上的input框自动聚焦

##vue页面

template

<div class="flex flexAlignCenter form_item">

    <span class="item_name">User name</span>
    
    <div class="item_right">
        <input type="text" v-model="query.username" ref="gain">
        <img src="../../assets/images/edit.png" alt="" class="icon_edit" @click="editName">
    </div>
</div>

methods

editName(){
    this.query.username = ''
    this.$nextTick( () =>{
        this.$refs.gain.focus()
    })
}