vue中el-autocomplete支持分页上拉加载功能

<template>
  <el-autocomplete
    :clearable="true"                                  //支持清空
    :title="searchStr"                                 // 鼠标移上去提示文案
    :trigger-on-focus="true"                           // 聚焦时是否触发下拉列表展示
    :fetch-suggestions="querySearchAsync"              // 筛选符合条件的数据
    :placeholder="placeholder"                         // 占位符提示信息
    v-scrollLoad="load"                                // 自定义上拉加载指令
    v-model="searchStr"                                // 搜索关键字
    popper-class="diy-autocomplete"                    // 下拉框自定义class控制样式
    class="el-autocomplete-component"                  // 给当前组件定义专属类名
    size="small"                                       // 组件显示尺寸
    ref="autocomplete"                                 // 用于后期获取dom元素
    @select="handleSelect"                             // 选中时触发事件
    @blur="handleBlur"                                 // 失去焦点时触发
    @clear="handleClear"                               // 清空数据时触发
  ></el-autocomplete>
</template>

// blurTxt： 记录上次失焦时 和 选中时的筛选字段
// blurArr： 记录上次失焦时 和 选中时已经查询到的数据
async querySearchAsync(queryString, cb) {
      if (this.blurTxt === queryString || !queryString) {
        cb(this.blurArr)
        return
      }
    },

    // 失焦事件
    handleBlur() {
      this.blurTxt = this.searchStr || ''
      this.blurArr = this.$refs['autocomplete'].$data.suggestions
    },
    // 过滤数据时及时更新筛选字段
    async querySearchAsync(queryString, cb) {
      this.blurTxt = searchVal
    },

/**
 * @param {Function} func
 * @param {number} wait
 * @param {boolean} immediate
 * @return {*}
 */
export function debounce(func, wait, immediate) {
  let timeout, args, context, timestamp, result

  const later = function() {
    // 据上一次触发时间间隔
    const last = +new Date() - timestamp

    // 上次被包装函数被调用时间间隔 last 小于设定时间间隔 wait
    if (last < wait && last > 0) {
      timeout = setTimeout(later, wait - last)
    } else {
      timeout = null
      // 如果设定为immediate===true，因为开始边界已经调用过了此处无需调用
      if (!immediate) {
        result = func.apply(context, args)
        if (!timeout) context = args = null
      }
    }
  }

  return function(...args) {
    context = this
    timestamp = +new Date()
    const callNow = immediate && !timeout
    // 如果延时不存在，重新设定延时
    if (!timeout) timeout = setTimeout(later, wait)
    if (callNow) {
      result = func.apply(context, args)
      context = args = null
    }

    return result
  }
}

  directives: {
    scrollLoad: {
      bind(el, binding, vnode) {
        let wrapDom = el.querySelector('.el-autocomplete-suggestion__wrap')
        let listDom = el.querySelector('.el-autocomplete-suggestion__wrap  .el-autocomplete-suggestion__list')
        // 滚动事件做防抖处理
        wrapDom.addEventListener(
          'scroll',
          debounce(e => {
            let condition = wrapDom.offsetHeight + wrapDom.scrollTop + 50 - listDom.offsetHeight
            if (condition > 0 && !vnode.context.loading) {
              binding.value()
            }
          }, 300),
          false
        )
      }
    }
  }

<el-autocomplete valueKey="nickName"></el-autocomplete>

    // 获取用户列表
    async getList(queryString) {
      let result = await searchUserList({
        pageNum: this.pageNum,
        pageSize: this.pageSize,
        searchValue: decodeURI(queryString)
      })
      this.total = result.total
      // 调用 callback 返回建议列表的数据
      result.rows &&
        result.rows.forEach(element => {
          // 学生展示 姓名+班级
          if (element.classList[0] && element.roleId === 101) {
            element.value = element.nickName + '-' + element.classList[0].className
          } else {
            // 非学生或者学生没有主班级展示 姓名+身份
            element.value = element.nickName + '-' + (element.roleName || '暂无角色ID')
          }
        })
      return result.rows
    },

<el-autocomplete > 
    <!--  输入框小图标插槽  -->
    <i class="el-icon-edit el-input__icon" slot="suffix"> </i> 
    <!--  搜索列表每一项展示  -->
    <template slot-scope="{ item }"> 
        <div class="name">{{ item.nickName }} - {{item.className}}</div>
    </template> 
</el-autocomplete>

    // 关闭加载圈
    closeLoading() {
      loadingInstance && loadingInstance.close && loadingInstance.close()
      loadingInstance = null
    },

    // 滚动加载
    async load() {
      this.closeLoading()
      // 加载到最后一页停止加载
      if (this.pageNum * this.pageSize > this.total) {
        return
      }
      this.pageNum++
      loadingInstance = Loading.service({
        target: document.querySelector('.el-autocomplete-suggestion'),
        fullscreen: false,
        spinner: 'el-icon-loading',
        lock: true,
        text: '加载中...'
      })
      let results = await this.getList(this.searchStr)
      this.closeLoading()
      this.pageNum * this.pageSize >= this.total ? results.push({ value: '暂无更多数据' }) : ''
      // 将数据添加到下拉列表
      this.$refs['autocomplete'].$data.suggestions = this.$refs['autocomplete'].$data.suggestions.concat(results)
    },

    // 清空搜索项
    handleClear() {
      this.blurTxt = ''
      this.blurArr = []
      this.$refs['autocomplete'].$data.suggestions = []
    },

    // 选中用户跳转至对应的页面
    handleSelect(item) {
      this.$refs['autocomplete'].$data.suggestions = this.blurArr = [item]
      this.blurTxt = this.searchStr || ''
      this.pageNum = 1
      this.total = 0
      ...
      //下拉选中的值
      // console.log(item)
    }

import axios from 'axios'
let pending = []; //声明一个数组用于存储每个ajax请求的取消函数和ajax标识
let cancelToken = axios.CancelToken;
let removePending = (ever) => {
    for (let p in pending) {
        if (pending[p].u === ever.url + '&' + ever.method) { //当当前请求在数组中存在时执行函数体 
            pending[p].f(); //执行取消操作
            pending.splice(p, 1); //把这条记录从数组中移除
        }
    }
}
var errorFlag = false;
var erFlag = false;
// 创建axios实例
const service = axios.create({
  // axios中请求配置有baseURL选项，表示请求URL公共部分
  baseURL: process.env.VUE_APP_BASE_API,
  // 超时
  timeout: 90000
})
// request拦截器
service.interceptors.request.use(
  config => {
     // 如果你是在老项目中开发就加一个限制，避免影响到原有的功能
    // if(config.url.indexOf('system/user/newsearch_list')!==-1){
    
      config && removePending(config); //在一个ajax发送前执行一下取消操作
      config.cancelToken = new cancelToken((c) => {
          // 这里的ajax标识我是用请求地址&请求方式拼接的字符串，当然你可以选择其他的一些方式
          pending.push({
              u: config.url + '&' + config.method,
              f: c
          });
      });
      
    // }
    return config
  },
  error => {
    console.log(error)
    Promise.reject(error)
  }
)

// 响应拦截器
service.interceptors.response.use(res => {
    const code = res.data.code
    if (code === 401) {
     ...         
    } else if (code !== 200) {
      if(!errorFlag){
        ...      
        return Promise.reject(res.data || {})
      }      
    } else {
      return res.data
    }
  },
  error => {
    // 单独处理取消请求导致的错误
    if(error.__CANCEL__){
      return false
    }
    if(!erFlag){
      Message({
        message: error.message,
        type: 'error',
        duration: 3 * 1000
      })
      return Promise.reject(error)
    }    
  }
)

.el-autocomplete-component {
  max-width: 230px;
  vertical-align: text-bottom;
  height: 50px;
  padding-top: 1px;
  cursor: pointer;
  /deep/ .el-input__inner {
    cursor: pointer;
    padding-left: 5px;
    padding-right: 8px;
    background: transparent;
    border: none;
    color: #fff;
    font-size: 14px;
    text-overflow: ellipsis;
    white-space: nowrap;
    overflow: hidden;
    &::placeholder {
      color: #bfbfbf;
      font-size: 12px;
    }
  }
}

.diy-autocomplete {
  .name {
    max-width: 180px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    height: 34px;
  }
}

<script>
import { searchUserList } from '@/api/system/user'  // 请求用户列表的接口
import { debounce } from '@/utils/index' // 防抖函数
import { Loading } from 'element-ui' // 下拉加载时的过渡loading
let loadingInstance = null

export default {
  data() {
    return {
      showAutocomplete: false,
      searchStr: '', //输入关键词的值
      pageNum: 1,
      pageSize: 20,
      total: 0, //筛选数据的总值
      placeholder: '请输入用户名/手机号/QQ',
      blurTxt: '', //记录失焦时搜索框中的文字，避免聚焦时重新筛选数据
      blurArr: [] //记录失焦时已经搜索出来的列表
    }
  },
  methods: {
    // 失焦事件
    handleBlur() {
      this.blurTxt = this.searchStr || ''
      this.blurArr = this.$refs['autocomplete'].$data.suggestions
    },
    // 清空搜索项
    handleClear() {
      this.blurTxt = ''
      this.blurArr = []
      this.$refs['autocomplete'].$data.suggestions = []
    },
    // 关闭加载圈
    closeLoading() {
      loadingInstance && loadingInstance.close && loadingInstance.close()
      loadingInstance = null
    },
    // 条件查询
    async querySearchAsync(queryString, cb) {
      this.$refs['autocomplete'].$data.suggestions = []
      if (this.blurTxt === queryString || !queryString) {
        cb(this.blurArr)
        return
      }
      this.handleClear()
      let searchVal = queryString
      // 后面所拼接的班级名称和角色不参与筛选字段中
      queryString.indexOf('-') !== -1 ? (searchVal = queryString.split('-')[0]) : ''
      this.pageNum = 1
      this.blurTxt = searchVal
      let results = await this.getList(searchVal)
      cb(results || [])
    },
    // 获取用户列表
    async getList(queryString) {
      let result = await searchUserList({
        pageNum: this.pageNum,
        pageSize: this.pageSize,
        searchValue: decodeURI(queryString)
      })
      this.total = result.total
      // 调用 callback 返回建议列表的数据
      result.rows &&
        result.rows.forEach(element => {
          // 学生展示 姓名+班级
          if (element.classList[0] && element.roleId === 101) {
            element.value = element.nickName + '-' + element.classList[0].className
          } else {
            // 非学生或者学生没有主班级展示 姓名+身份
            element.value = element.nickName + '-' + (element.roleName || '暂无角色ID')
          }
        })
      return result.rows
    },
    // 滚动加载
    async load() {
      this.closeLoading()
      // 加载到最后一页停止加载
      if (this.pageNum * this.pageSize > this.total) {
        return
      }
      this.pageNum++
      loadingInstance = Loading.service({
        target: document.querySelector('.el-autocomplete-suggestion'),
        fullscreen: false,
        spinner: 'el-icon-loading',
        lock: true,
        text: '加载中...'
      })
      let results = await this.getList(this.searchStr)
      this.closeLoading()
      this.pageNum * this.pageSize >= this.total ? results.push({ value: '暂无更多数据' }) : ''
      // 将数据添加到下拉列表
      this.$refs['autocomplete'].$data.suggestions = this.$refs['autocomplete'].$data.suggestions.concat(results)
    },
    // 选中用户跳转至对应的页面
    handleSelect(item) {
      this.$refs['autocomplete'].$data.suggestions = this.blurArr = [item]
      this.blurTxt = this.searchStr || ''
      this.pageNum = 1
      this.total = 0
      let routeData = {}
      if (item.roleId === 101) {
        // 学生
        routeData = this.$router.resolve({ path: '/personInf/student', query: { userId: item.userId } })
      } else {
        // 非学生
        routeData = this.$router.resolve({
          path: '/userManagement/user',
          query: { userInfo: item.nickName ,roleId: item.roleId||''}
        })
      }
      window.open(routeData.href, '_blank')
      //下拉选中的值
      // console.log(item)
    }
  },
  directives: {
    scrollLoad: {
      bind(el, binding, vnode) {
        let wrapDom = el.querySelector('.el-autocomplete-suggestion__wrap')
        let listDom = el.querySelector('.el-autocomplete-suggestion__wrap  .el-autocomplete-suggestion__list')
        // 滚动事件做防抖处理
        wrapDom.addEventListener(
          'scroll',
          debounce(e => {
            let condition = wrapDom.offsetHeight + wrapDom.scrollTop + 50 - listDom.offsetHeight
            if (condition > 0 && !vnode.context.loading) {
              binding.value()
            }
          }, 300),
          false
        )
      }
    }
  }
}
</script>