data () {
 return {
 // 可用的文章列表
 columnItems: [],
 // 是否正在加载
 isLoading: [false, false, false],
 // 选择框搜索输入的值
 searchColumn1: '',
 searchColumn2: '',
 searchColumn3: ''
 }
 },

<label>推荐专栏1</label>
 <v-combobox :items="columnItems"
 :loading="isLoading[0]"
 :search-input.sync="searchColumn1"
 ...
 >
 ...
 </v-combobox>
 <label>推荐专栏2</label>
 <v-combobox
 :items="columnItems"
 :loading="isLoading[1]"
 :search-input.sync="searchColumn2"
 ...
 >
 ...
 </v-combobox>
 <label>推荐专栏3</label>
 <v-combobox
 :items="columnItems"
 :loading="isLoading[2]"
 :search-input.sync="searchColumn3"
 ...
 >
 ...
 </v-combobox>

watch: {
 searchColumn1 (val) {
 this.getColumns(val, 0)
 },
 searchColumn2 (val) {
 this.getColumns(val, 1)
 },
 searchColumn3 (val) {
 this.getColumns(val, 2)
 }
 },
 ...
 methods: {
 getColumns: function (searchValue, index) {
 // Items have already been requested
 if (this.isLoading[index]) return
 this.isLoading[index] = true
 let vm = this
 let options = {
 page: 1
 }
 if (searchValue) {
 options.title = searchValue.trim()
 } else {
 vm.columnItems = []
 vm.isLoading[index] = false
 return
 }
 // console.log(options)
 vm.$store.dispatch('getAllColumns', options).then(function (columns) {
 if (columns && columns.length) {
 vm.columnItems = columns
 }
 vm.isLoading[index] = false
 })
 }
 }

import _ from 'lodash'
 ...
 created: function () {
 this.getColumns = _.debounce(this.getColumns, 500)
 },