react实现移动端下拉菜单

项目中要实现类似与vant的DropdownMenu:下拉菜单。看了vans 的效果 其实也没什么难度,于是动手鲁了一个这样的组件。 项目的技术栈为react全家桶+material UI + ant Design mobile。

vans的效果

我自己实现的效果

思路

  • 常规做法
    获取dom元素,动态修改选中dom的innerHtml。
    当然这种方式不是react推荐的
    复制代码
  • 我的做法
    既然react不推荐直接操作dom元素,那可以采用动态动态修改class的方式达到效果,例如:
    let cls ="normal"
    div未被选中时
    <div className={cls}/> 
    div被选中时
    cls+=" current"
    <div className ={cls}>
    复制代码

实现步骤

  • 顶部tab采用三个div的方式布局,由于需要动态修改tab上的标题,所以定义一个数组,reducer中的tab数据结构如下

    let tabs = {};
    tabs[TABKAY.AREA] = {
    key: TABKAY.AREA,
    text: "全部区域",
    obj: {}
    };
    tabs[TABKAY.SORT] = {
    key: TABKAY.SORT,
    text: "综合排序",
    obj: {}
    };
    tabs[TABKAY.FILTER] = {
    key: TABKAY.FILTER,
    text: "筛选",
    obj: SX
    };
    const initialState = {
    areas: [{ id: "", name: "全部区域" }],
    tabs: tabs,
    actionKey: TABKAY.AREA,// 标识了当前选中tab
    closePanel: true // 标识panel div 是否显示
    };
    复制代码
  • tabUI组件的页面容器渲染方法

    renderTabs() {
    const { tabs, actionKey, closePanel } = this.props;
    //---------
    if (!closePanel) {
      fixedBody();
    } else {
      looseBody();
    }
    //---------
    
    let aray = [];
    for (let key in tabs) {
      let item = tabs[key];
      let cls = item.key + " item";
      if (item.key === actionKey && !closePanel) {
        cls += " current";
      }
    
      aray.push(
        <div className={cls} key={item.key} onClick={() => this.onChangeTab(item.key)}>
          {item.text}
        </div>);
    }
    
    return aray;
    }
    复制代码
  • 样式 :这里边有个技巧,就是利用了css元素选择器的伪类的方式巧妙实现了箭头以及箭头的旋转动画

    .item {
    flex: 1;
    font-size: 15px;
    border-right: 0.5px solid #eaeaea;
    text-align: center;
    
    &:last-child {
      border: none;
    }
    
    &.AREA:after, &.SORT:after, &.FILTER:after {
      content: "";
      display: inline-block;
      width: 5px;
      height: 5px;
      margin-bottom: 2px;
      margin-left: 6px;
      border: 2px solid #666;
      border-width: 0 2px 2px 0;
      transform: rotate(45deg);
      -webkit-transform: rotate(45deg);
      -webkit-transition: .3s;
      transition: .3s;
    }
    
    &.current {
      color: #0084ff;
    }
    
    &.current:after {
      border-color: #0084ff;
      transform: rotate(225deg);
      -webkit-transform: rotate(225deg);
    }
    复制代码
  • chrome 查看元素

全部区域tab被选中:

综合tab被选中

每次点击不同的tab时 都会自动的渲染current这个css样式,这样就实现了下拉菜单的功能。

完整代码

/**
 * Class:
 * Author: miyaliunian
 * Date: 2019/5/26
 * Description:  tabs 选择器
 *  医院列表
 */
import React, { Component } from "react";
import { ZHPX, TABKAY } from "@api/Constant";
//Util
import { fixedBody, looseBody } from "@utils/fixRollingPenetration";
//Redux
import { connect } from "react-redux";
import { bindActionCreators } from "redux";
import { actions as tabActions, getTabs, getAreasList, getActionKey, getClosePanel } from "@reduxs/modules/tabs";
import { actions as hospitalActions,} from "@reduxs/modules/hospital";

//样式
import "./tabs.less";

class Tabs extends Component {
  
  /**
   *  变化当前点击的item状态 同时filter 请求
   * @param filterItem  当前选中的元素
   * @param key   哪个tab是选中状态
   */
  changeDoFilter(filterItem, key, event) {
    const { tabActions: { changeFilter }, hospitalActions:{filterHosiContentList} } = this.props;
    event.stopPropagation();
    changeFilter(filterItem, key, (filter) => {
      filterHosiContentList(filter);
    });
  }

  /**
   * 筛选tab确定按钮
   * @param event
   */
  filterPanel(event) {
    const {tabActions:{closePanelAction}, tabs,hospitalActions:{filterHosiContentList}} = this.props;
    event.stopPropagation();
    closePanelAction(()=>{
      filterHosiContentList(tabs)
    })
  }

  /**
   * 点击切换Tab
   * @param key
   */
  onChangeTab(key) {
    const { actionKey,tabActions: { changeTab }  } = this.props;
    let closePanel = false;
    //如果前后点击的是同一个tab 就关闭panel
    if (actionKey === key && !this.props.closePanel) {
      closePanel = true;
    }
    closePanel ? looseBody() : fixedBody();
    changeTab(key, closePanel);
  }

  /**
   * 渲染顶部tab
   */
  renderTabs() {
    const { tabs, actionKey, closePanel } = this.props;
    //---------
    if (!closePanel) {
      fixedBody();
    } else {
      looseBody();
    }
    //---------

    let aray = [];
    for (let key in tabs) {
      let item = tabs[key];
      let cls = item.key + " item";
      if (item.key === actionKey && !closePanel) {
        cls += " current";
      }

      aray.push(
        <div className={cls} key={item.key} onClick={() => this.onChangeTab(item.key)}>
          {item.text}
        </div>);
    }

    return aray;
  }

  /**
   * 全部区域
   * @returns {*}
   */
  renderAreaContent() {
    const { areasList } = this.props;
    return areasList.map((item, index) => {
      let cls = item.active + " area-item";
      return (
        <li key={index} className={"area-item"} onClick={(e) => this.changeDoFilter(item, TABKAY.AREA, e)}>
          {item.name}
        </li>
      );
    });
  }


  /**
   * 全部排序
   * @returns {any[]}
   */
  renderSORTContent() {
    let sortList = ZHPX;
    return sortList.map((item, index) => {
      let cls = item.action ? "type-item active" : "type-item";

      return (
        <li key={index} className={cls} onClick={(e) => this.changeDoFilter(item, TABKAY.SORT, e)}>
          {item.name}
        </li>
      );
    });
  }


  /**
   * 筛选
   * @returns {*}
   */

  renderFilterInnerContent(items/*filterList*/) {
    return items.map((item, index) => {
      let cls = "cate-box";
      if (item.active) {
        cls += " active";
      }

      return (
        <div key={index} className={cls} onClick={(e) => this.changeDoFilter(item, TABKAY.FILTER, e)}>
          {item.name}
        </div>
      );
    });

  }

  renderFILTERContent() {
    let filterList = [];
    const { tabs } = this.props;
    filterList = tabs[TABKAY.FILTER].obj;
    return filterList.map((item, index) => {
      return (
        <li key={index} className={"filter-item"}>
          <p className={"filter-title"}>{index == 0 ? `医院类型: ${item.groupTitle}` : `医院等级: ${item.groupTitle}`}</p>
          <div className={"item-content"}>
            {this.renderFilterInnerContent(item.items, filterList)}
          </div>
        </li>
      );
    });
  }

  /**
   * 渲染过滤面板
   */
  renderContent() {
    const { tabs, actionKey } = this.props;
    let array = [];
    for (let key in tabs) {
      let item = tabs[key];
      let cls = item.key + "-panel";
      if (item.key === actionKey) {
        cls += " current";
      }

      // 全部区域
      if (item.key === TABKAY.AREA) {
        array.push(
          <ul key={item.key} className={cls}>
            {this.renderAreaContent()}
          </ul>
        );
      } else if (item.key === TABKAY.SORT) {
        // 综合排序
        array.push(
          <ul key={item.key} className={cls}>
            {this.renderSORTContent()}
          </ul>
        );
      } else if (item.key === TABKAY.FILTER) {
        // 筛选
        array.push(
          <ul key={item.key} className={cls}>
            {this.renderFILTERContent()}
            <div className={"filterBtn"} onClick={(e) => this.filterPanel(e)}>
              确定
            </div>
          </ul>
        );
      }

    }
    return array;
  }


  render() {
    const { closePanel, tabActions: { closePanelAction } } = this.props;
    let cls = "panel";
    if (!closePanel) {
      cls += " show";
    } else {
      cls = "panel";
    }
    return (
      <div className={"tab-header"}>
        <div className={"tab-header-top border-bottom"}>
          {this.renderTabs()}
        </div>
        <div className={cls} onClick={() => closePanelAction(()=>{})}>
          <div className={"panel-inner"}>
            {this.renderContent()}
          </div>
        </div>
      </div>
    );
  }


  componentDidMount() {
    const { areasList, tabActions: { loadAreas } } = this.props;
    if (areasList && areasList.length !== 1) {
      return;
    }
    loadAreas();
  }
}

const mapStateToProps = state => {
  return {
    areasList: getAreasList(state),
    tabs: getTabs(state),
    actionKey: getActionKey(state),
    closePanel: getClosePanel(state)
  };
};

const mapDispatchToProps = dispatch => {
  return {
    tabActions: bindActionCreators(tabActions, dispatch),
    hospitalActions: bindActionCreators(hospitalActions, dispatch)
  };
};

export default connect(mapStateToProps, mapDispatchToProps)(Tabs);
复制代码
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