一、状态

什么是状态

import React, { Component } from "react";

export default class App extends Component {
  state = {
    mytext: "收藏",
    myShow: true,
  };

  render() {
    return (
      <div>
        <h1>状态学习调试</h1>
        <button
          onClick={() => {
            this.setState({
              //   mytext: "取消收藏",
              myShow: !this.state.myShow,
            });

            if (this.state.myShow) {
              console.log("收藏的逻辑");
            } else {
              console.log("取消收藏的逻辑");
            }
          }}
        >
          {this.state.myShow ? "收藏" : "取消收藏"}
        </button>
      </div>
    );
  }
}

另一种写法：构造函数—快捷键 rcs

export default class App extends Component {
  constructor(props) {
    super(props);

    this.state = {
      mytext: "收藏",
      myShow: true,
      myname: true,
    };
  }

  render() {

二、循环渲染

.map()映射

import React, { Component } from "react";

export default class App extends Component {
  constructor(props) {
    super(props);

    this.state = {
      list: ["111", "222", "333"],
    };
  }

  render() {
    
    return (
      <div>
        <ul>
          {this.state.list.map((item) => {
            return <li key={item}>{item}</li>;
          })}
        </ul>
      </div>
    );
  }
}

加Key的原因

为了列表的复用和重排

避免key值相同的改法：
更改接受的数据

import React, { Component } from "react";

export default class App extends Component {
  constructor(props) {
    super(props);

    this.state = {
      //   list: ["111", "222", "333"],
      list: [
        {
          id: 1,
          text: "1111",
        },
        {
          id: 2,
          text: "2222",
        },
      ],
    };
  }

  render() {
    return (
      <div>
        <ul>
          {this.state.list.map((item) => {
            return <li key={item.id}>{item.text}</li>;
          })}
        </ul>
      </div>
    );
  }
}

三级标题

四级标题

五级标题

六级标题