[JavaScript知识库]React项目-Note:初始化项目

第一步骤：创建项目

create-react-app react_note

第二步骤：运行项目

npm start

第三步骤：项目目录修改
情况src目录下的所有文件，新建index.js文件；
在src目录下新建Page目录，在Page目录下新建index.js

src/Page/index.js

import React from "react";

class Index extends React.Component{

    render() {
        return(
            <div>

                helllo pgae
            </div>
        )
    }
}
export default Index;

src/index.js

import ReactDOM from 'react-dom';
import Index from './Page/index'
ReactDOM.render( 
<Index/>,
document.getElementById('root')
);

这样写存在warning

 ReactDOM.render is no longer supported in React 18.
  Use createRoot instead

即react18不再支持ReactDOM,使用createRoot替代

src/index.js文件修改如下

import ReactDOM from 'react-dom';
import Index from './Page/index';

const container  = document.getElementById('root');

const root = ReactDOM.createRoot(container );
root.render(<Index />)

仍有warning

src/index.js文件修改如下

import * as ReactDOM from 'react-dom/client';
import Index from './Page/index';

const container  = document.getElementById('root');

const root = ReactDOM.createRoot(container );
root.render(<Index />)

现在就是干干净净的项目了

package.json文件

{
  "name": "react_note",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@testing-library/jest-dom": "^5.16.3",
    "@testing-library/react": "^12.1.4",
    "@testing-library/user-event": "^13.5.0",
    "react": "^18.0.0",
    "react-dom": "^18.0.0",
    "react-scripts": "5.0.0",
    "web-vitals": "^2.1.4"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": [
      "react-app",
      "react-app/jest"
    ]
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  }
}