React native 已有项目升级兼容web

基础 

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 深入理解Webpack及Babel的使用 - 掘金

Introduction to React Native for Web // React Native for Web

Webpack 是一个现代的 JavaScript 应用程序的静态模块打包工具，它将应用程序所依赖的各种资源（js、css、图片等）视为模块，通过 loader 转换这些模块，最后打包成符合生产环境部署的静态资源。

Webpack 的运行机制基于一条简单的原则：一切文件皆模块。因此，Webpack 在构建应用程序时，会先从入口模块开始递归解析模块依赖，然后通过 loader 处理各种类型的模块，最后打包成一个或多个浏览器可识别的静态资源。

Webpack 的基本配置包括 entry、output、module 和 plugins 四个部分。其中，entry 指定了入口模块，output 指定了输出目录和输出文件名，module 则用于配置 loader 和其他的一些规则，plugins 则是用于扩展 Webpack 功能的插件。

在使用 Webpack 进行项目开发时，我们通常需要使用 Babel 将 ES6+ 代码转换成浏览器兼容的 ES5 代码。Babel 的作用是将 JavaScript 新特性转换成浏览器支持的语法，例如箭头函数、解构赋值等。而 Loader 则是 Webpack 中用于处理各种类型文件的工具，例如将 css 转换成 JavaScript 对象、将图片转换成 data URL 等。

Babel是一个JavaScript编译器，可以将最新版本的JavaScript转换为向后兼容的代码，以便在旧版浏览器或其他环境中运行。Babel的作用是让我们使用最新的JavaScript语法特性，而不必担心浏览器是否支持这些特性。

过程

yarn add react-dom react-native-web
yarn add react-native-reanimated
yarn add -D babel-plugin-react-native-web
yarn add -D babel-loader url-loader webpack webpack-cli webpack-dev-server
yarn add -D babel-plugin-react-native-web
#每次打包发布时自动清理掉 dist 目录中的旧文件，
yarn add -D clean-webpack-plugin


#html-webpack-plugin的主要作用就是在webpack构建后生成html文件，同时把构建好入口js文件引入到生成的html文件中。
yarn add -D html-webpack-plugin

webpack.config.js

const path = require('path');
const {CleanWebpackPlugin} = require('clean-webpack-plugin');

const webpack = require('webpack');
const HtmlWebpackPlugin = require('html-webpack-plugin');

const appDirectory = path.resolve(__dirname);
// const {presets} = require(`${appDirectory}/babel.config.js`);

const compileNodeModules = [
  // Add every react-native package that needs compiling
  // 'react-native-gesture-handler',
].map((moduleName) => path.resolve(appDirectory, `node_modules/${moduleName}`));

const baseProjectSource = [
  path.resolve(appDirectory, 'web/index.web.js'), // Entry to your application
  path.resolve(appDirectory, 'web/App.web.js'), // Change this to your main App file
  path.resolve(appDirectory, './src'),
];


const babelLoaderConfiguration = {
  test: /\.(js|jsx|ts|tsx)$/,
  // Add every directory that needs to be compiled by Babel during the build.
  include: baseProjectSource,
  use: {
    loader: 'babel-loader',
    options: {
      cacheDirectory: true,
      // The 'react-native' preset is recommended to match React Native's packager
      presets: ['module:metro-react-native-babel-preset'],
      // Re-write paths to import only the modules needed by the app
      plugins: ['react-native-web', 'react-native-reanimated/plugin'],
    },
  },
};


const imageLoaderConfiguration = {
  test: /\.(gif|jpe?g|png)$/,
  use: {
    loader: 'url-loader',
    options: {
      name: '[name].[ext]',
    },
  },
};

module.exports = {
  entry: {
    app: path.join(appDirectory, 'web/index.web.js'),
  },
  output: {
    path: path.resolve(appDirectory, 'dist'),
    publicPath: '/',
    filename: 'upup.bundle.js',
  },
  resolve: {
    // If you're working on a multi-platform React Native app, web-specific
    // module implementations should be written in files using the extension
    // `.web.js`.
    extensions: ['.web.tsx', '.web.ts', '.tsx', '.ts', '.web.js', '.js'],
    alias: {
      'react-native$': 'react-native-web',
    },
  },
  module: {
    rules: [
      babelLoaderConfiguration,
      imageLoaderConfiguration,
    ],
  },
  devServer: {
    port: 8080,
    historyApiFallback: true,
    open: !process.env.CI,
  }, 
  plugins: [
    new CleanWebpackPlugin({
      cleanOnceBeforeBuildPatterns: [
        '**/*'
      ]
    }),
    // `process.env.NODE_ENV === 'production'` must be `true` for production
    // builds to eliminate development checks and reduce build size. You may
    // wish to include additional optimizations.
    new webpack.DefinePlugin({
      'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV || 'development'),
      __DEV__: process.env.NODE_ENV === 'production' || true
    }),
    new HtmlWebpackPlugin({
      template: path.join(appDirectory, 'web/index.html'),
    }),
    new webpack.HotModuleReplacementPlugin(),
    new webpack.DefinePlugin({
      // See: https://github.com/necolas/react-native-web/issues/349
      __DEV__: JSON.stringify(true),
    }),
  ],
};

index.html

index.web.js

import {AppRegistry} from 'react-native';
import appInfo from '../app.json';
import App from './App.web';


AppRegistry.registerComponent(appInfo.name, () => App);
AppRegistry.runApplication(appInfo.name, {
  initialProps: {},
  rootTag: document.getElementById('app-root'),
});

App.web.js

import React from 'react';
import FaqTestnet from '../src/screen/FaqTestnet';
import AboutTestnet from '../src/screen/AboutTestnet';
import 'react-native-gesture-handler';
import {NavigationContainer} from '@react-navigation/native';
import {
  createStackNavigator,
  CardStyleInterpolators,
} from '@react-navigation/stack';
import Color from "../src/app/Color";
import DarkTheme from '../src/app/DarkTheme';

const Stack = createStackNavigator();

const config = {
  screens: {
    FaqTestnet: 'faqtestnet',
    AboutTestnet: 'abouttestnet',
  },
};

const linking = {
  prefixes: ['http://tokshow.io',  'http://localhost:8080', 'http://127.0.0.1:5500/'],
  config,
};

function App() {
  return (
    Loading...} theme={DarkTheme}>
      
        
        
      
    
  );
}

export default App;

package.json

  "scripts": {
    "web:release": "export NODE_ENV=production && rm -rf dist/ && webpack --config ./webpack.config.js",
    "web": "export NODE_ENV=development && webpack-dev-server --config ./webpack.config.js",

参考

How to Make Your React Native Apps Work on the Web