react写一个select组件的实现代码

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import {MobileSelect, MobileOption} from '../../components/MobileSelect';

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  {
   (clarity || []).map((item, i) => {
    return (
     {item.title}
    );
   })
  }
 

import {observable} from 'mobx';
import {observer} from 'mobx-react';
import React from 'react';
import {Icon} from 'antd';
import './index.less';

interface IProps {
 disabled&＃63;: boolean;
 onChange&＃63;: (value) => void;
 value&＃63;: string | number;
 style&＃63;: React.CSSProperties;
 className&＃63;: string;
}
@observer
export class MobileSelect extends React.Component {
 @observable showOption = false;   // 是否弹出下拉框
 @observable value: any = '';    // 当前选中的value值
 @observable text: any = '';     // 选中的value值对应的文本
 @observable cell: any;       // 组件的dom节点
 componentDidMount(): void {
  // 获取选择框的ref，当在组件外点击时的时候收起下拉框
  document.addEventListener('click', (e) => {
   if (this.cell && this.cell !== e.target && !this.cell.contains(e.target)) {
    this.showOption = false;
   }
  }, true);
 }
 componentWillReceiveProps(nextProps: Readonly, nextContext: any): void {
  // 根据传入的value值，遍历children，找到对应值的展示文本
  if (nextProps.value !== this.props.value || nextProps.children !== this.props.children) {
   React.Children.map(this.props.children, (child, index) => {
    if (nextProps.value === child.props.value) {
     this.text = child.props.children;
    }
   });
  }
 }
 render(): React.ReactNode {
  const {children, value} = this.props;
  console.log(value);
  return (
   
 this.cell = node}
   >
    
 {
      // 禁用不能弹出下拉框
      if (!this.props.disabled) {
       this.showOption = !this.showOption;
      }
     }}
    >
     
     {this.text}
    
    

     {
      React.Children.map(children, (child, index) => {
       // 设置选中option和未选中option的样式
       let optiOnClassName= '';
       if (this.props.value === child.props.value) {
        optiOnClassName= child.props.className &＃63; child.props.className + ' option-item selected' : 'option-item selected';
       } else {
        optiOnClassName= child.props.className + ' option-item';
       }
       return (
        
 {     // 为了在父组件给子组件添加onClick事件，包裹了一层div
          // 有无onChange事件都能改变值
          if (this.props.value && this.props.onChange) {
           this.props.onChange(child.props.value);
          } else {
           this.text = child.props.children;
           this.value = child.props.value;
          }
          console.log(this.value);
          this.showOption = !this.showOption;
         }}
         style={this.props.style}
         className={optionClassName}
        >{child}
       );
      })
     }
    
   
  );
 }
}
interface OptionProps {
 value&＃63;: string | number;
 className&＃63;: string;
 style&＃63;: React.CSSProperties;
}
export class MobileOption extends React.Component {
 render(): React.ReactNode {
  const {children} = this.props;
  return (
   

    {children}
   
  );
 }
}

.Mobile-Select {
 display: inline-block;
 min-width: 100px;
 margin: 0 6px;
 .select-wrap {
  border: 1px solid #e0c0a2;
  border-radius: 4px;
  padding: 5px 11px;
  display: flex;
  flex-direction: row-reverse;
  justify-content: space-between;
  align-items: center;
  .select-icon {
   transition: .3s;
   float: right;
  }
 }
 .option-wrap {
  box-shadow: 0 0 5px #333;
  z-index: 1000;
  border-radius: 5px;
  .option-item {
   background-color: #fff;
   padding: 2px 11px;
   min-width: 100px;
   &.selected {
    background-color: #fbe6d0;
   }
  }
 }
}

import React from "react";
import { render } from "react-dom";

class App extends React.Component {
 constructor(props) {
  super(props);
  this.state = {
   projects: [],
   value: ""
  };
 }
 componentDidMount() {
  // 模拟ajax调用，成功之后把需要改变的默认值赋值给this.state.value
  setTimeout(() => {
   this.setState({
    projects: [
     { id: 1, name: "花生" },
     { id: 2, name: "苹果" },
     { id: 3, name: "杨桃" }
    ],
    value: 1
   });
  }, 3000);
 }
 handleClick() {
  this.setState({
   projects: [
    { id: 4, name: "水果" },
    { id: 5, name: "西瓜" },
    { id: 6, name: "哈哈哈" }
   ],
   value: 4
  });
 }
 handleChange = e => {
  this.setState({
   value: e.target.value
  });
 };
 render() {
  let projects = this.state.projects;
  return (
   

    异步拉取数据
    {/* 这里不用再去判断project的长度是否大于0，在ajax里面做判断就行，如果小于零或者不存在它就是默认值 */}
    
     {projects.length > 0 &&
      projects.map((item, i) => {
       return (
        
         {item.name}
        
       );
      })}
    
   
  );
 }
}

render(, document.getElementById("root"));