一、安装
npm install -g create-react-app二、创建react应用
create-react-app 是全局命令来创建 react 项目
$ create-react-app react-cli-demo
Creating a new React app in G:\GitHub\React-demo\react-cli-demo.
Installing packages. This might take a couple of minutes.
Installing react, react-dom, and react-scripts...
1. 主要依赖 react,react-dom,react-scripts
2. 生成目录结构
create-react-app生成项目目录结构
3. package.json
没有配置文件（webpack.config.js）
三、npm 命令
1、npm start
"start": "react-scripts start"
不是熟悉的"node scripts/start.js"
2、react-scripts 是什么？
react-scripts是create-react-app生成项目所有的依赖。
通常情况下，我们创建spa应用时是使用npm安装项目依赖，在通过配置webpack.config.js进行配置，搭建好环境后在src编写源代码。而create-react-app是自动构建，在package.json中只有react-scripts作为依赖，而在reacr-scripts中已经配置好了项目所有需要的。
有一下支持：
React, JSX, ES6, and Flow syntax support.
Language extras beyond ES6 like the object spread operator.
Import CSS and image files directly from JavaScript.
Autoprefixed CSS, so you don’t need -webkit or other prefixes.
A build script to bundle JS, CSS, and images for production, with sourcemaps.
A dev server that lints for common errors.
从react，es6，babel,webpack编辑到打包，react-scripts都做了。
3、react-scripts源码
打开mode-modules\react-scripts\bin \react-scripts.js
'use strict';
const spawn = require('react-dev-utils/crossSpawn');
const args = process.argv.slice(2);
const scriptIndex = args.findIndex(
x => x === 'build' || x === 'eject' || x === 'start' || x === 'test'
);
const script = scriptIndex === -1 ? args[0] : args[scriptIndex];
const nodeArgs = scriptIndex > 0 ? args.slice(0, scriptIndex) : [];
switch (script) {
case 'build':
case 'eject':
case 'start':
case 'test': {
const result = spawn.sync(
'node',
nodeArgs
.concat(require.resolve('../scripts/' + script)) //根据npm命令引用不同文件
.concat(args.slice(scriptIndex + 1)),
{ stdio: 'inherit' }
);
if (result.signal) {
if (result.signal === 'SIGKILL') {
console.log(
'The build failed because the process exited too early. ' +
'This probably means the system ran out of memory or someone called ' +
'`kill -9` on the process.'
);
} else if (result.signal === 'SIGTERM') {
console.log(
'The build failed because the process exited too early. ' +
'Someone might have called `kill` or `killall`, or the system could ' +
'be shutting down.'
);
}
process.exit(1);
}
process.exit(result.status);
break;
}
default:
console.log('Unknown script "' + script + '".');
console.log('Perhaps you need to update react-scripts?');
console.log(
'See: https://github.com/facebookincubator/create-react-app/blob/master/packages/react-scripts/template/README.md#updating-to-new-releases'
);
break;
}
scripts文件
// start.js
'use strict';
// Do this as the first thing so that any code reading it knows the right env.
process.env.BABEL_ENV = 'development';
process.env.NODE_ENV = 'development';
// Makes the script crash on unhandled rejections instead of silently
// ignoring them. In the future, promise rejections that are not handled will
// terminate the Node.js process with a non-zero exit code.
process.on('unhandledRejection', err => {
throw err;
});
// Ensure environment variables are read.
require('../config/env');
const fs = require('fs');
const chalk = require('chalk');
const webpack = require('webpack'); //引入webpack
const WebpackDevServer = require('webpack-dev-server'); // 引入webpack-dev-server
const clearConsole = require('react-dev-utils/clearConsole');
const checkRequiredFiles = require('react-dev-utils/checkRequiredFiles');
const {
choosePort,
createCompiler,
prepareProxy,
prepareUrls,
} = require('react-dev-utils/WebpackDevServerUtils');
const openBrowser = require('react-dev-utils/openBrowser');
const paths = require('../config/paths'); //文件路径
const config = require('../config/webpack.config.dev');
const createDevServerConfig = require('../config/webpackDevServer.config');
const useYarn = fs.existsSync(paths.yarnLockFile);
const isInteractive = process.stdout.isTTY;
// Warn and crash if required files are missing
if (!checkRequiredFiles([paths.appHtml, paths.appIndexJs])) {
process.exit(1);
}
// Tools like Cloud9 rely on this.
const DEFAULT_PORT = parseInt(process.env.PORT, 10) || 3000; // 端口3000，可以修改在执行npm run start
const HOST = process.env.HOST || '0.0.0.0';
if (process.env.HOST) {
console.log(
chalk.cyan(
`Attempting to bind to HOST environment variable: ${chalk.yellow(
chalk.bold(process.env.HOST)
)}`
)
);
console.log(
`If this was unintentional, check that you haven't mistakenly set it in your shell.`
);
console.log(`Learn more here: ${chalk.yellow('http://bit.ly/2mwWSwH')}`);
console.log();
}
// We attempt to use the default port but if it is busy, we offer the user to
// run on a different port. `choosePort()` Promise resolves to the next free port.
choosePort(HOST, DEFAULT_PORT)
.then(port => {
if (port == null) {
// We have not found a port.
return;
}
const protocol = process.env.HTTPS === 'true' ? 'https' : 'http';
const appName = require(paths.appPackageJson).name;
const urls = prepareUrls(protocol, HOST, port);
// Create a webpack compiler that is configured with custom messages.
const compiler = createCompiler(webpack, config, appName, urls, useYarn);
// Load proxy config
const proxySetting = require(paths.appPackageJson).proxy;
const proxyConfig = prepareProxy(proxySetting, paths.appPublic);
// Serve webpack assets generated by the compiler over a web sever.
const serverConfig = createDevServerConfig(
proxyConfig,
urls.lanUrlForConfig
);
const devServer = new WebpackDevServer(compiler, serverConfig);
// Launch WebpackDevServer.
devServer.listen(port, HOST, err => {
if (err) {
return console.log(err);
}
if (isInteractive) {
clearConsole();
}
console.log(chalk.cyan('Starting the development server...\n'));
openBrowser(urls.localUrlForBrowser);
});
['SIGINT', 'SIGTERM'].forEach(function(sig) {
process.on(sig, function() {
devServer.close();
process.exit();
});
});
})
.catch(err => {
if (err && err.message) {
console.log(err.message);
}
process.exit(1);
});
// path.js 文件
// @remove-on-eject-begin
/**
* Copyright (c) 2015-present, Facebook, Inc.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
// @remove-on-eject-end
'use strict';
const path = require('path');
const fs = require('fs');
const url = require('url');
// Make sure any symlinks in the project folder are resolved:
// https://github.com/facebookincubator/create-react-app/issues/637
const appDirectory = fs.realpathSync(process.cwd());
const resolveApp = relativePath => path.resolve(appDirectory, relativePath);
const envPublicUrl = process.env.PUBLIC_URL;
function ensureSlash(path, needsSlash) {
const hasSlash = path.endsWith('/');
if (hasSlash && !needsSlash) {
return path.substr(path, path.length - 1);
} else if (!hasSlash && needsSlash) {
return `${path}/`;
} else {
return path;
}
}
const getPublicUrl = appPackageJson =>
envPublicUrl || require(appPackageJson).homepage;
// We use `PUBLIC_URL` environment variable or "homepage" field to infer
// "public path" at which the app is served.
// Webpack needs to know it to put the right <script> hrefs into HTML even in
// single-page apps that may serve index.html for nested URLs like /todos/42.
// We can't use a relative path in HTML because we don't want to load something
// like /todos/42/static/js/bundle.7289d.js. We have to know the root.
function getServedPath(appPackageJson) {
const publicUrl = getPublicUrl(appPackageJson);
const servedUrl =
envPublicUrl || (publicUrl ? url.parse(publicUrl).pathname : '/');
return ensureSlash(servedUrl, true);
}
// config after eject: we're in ./config/
module.exports = { // 熟悉的各种文件的配置，也要求了在项目中index.js和index.html不能改名
dotenv: resolveApp('.env'),
appBuild: resolveApp('build'),
appPublic: resolveApp('public'),
appHtml: resolveApp('public/index.html'),
appIndexJs: resolveApp('src/index.js'),
appPackageJson: resolveApp('package.json'),
appSrc: resolveApp('src'),
yarnLockFile: resolveApp('yarn.lock'),
testsSetup: resolveApp('src/setupTests.js'),
appNodeModules: resolveApp('node_modules'),
publicUrl: getPublicUrl(resolveApp('package.json')),
servedPath: getServedPath(resolveApp('package.json')),
};
// @remove-on-eject-begin
const resolveOwn = relativePath => path.resolve(__dirname, '..', relativePath);
// config before eject: we're in ./node_modules/react-scripts/config/
module.exports = {
dotenv: resolveApp('.env'),
appPath: resolveApp('.'),
appBuild: resolveApp('build'),
appPublic: resolveApp('public'),
appHtml: resolveApp('public/index.html'),
appIndexJs: resolveApp('src/index.js'),
appPackageJson: resolveApp('package.json'),
appSrc: resolveApp('src'),
yarnLockFile: resolveApp('yarn.lock'),
testsSetup: resolveApp('src/setupTests.js'),
appNodeModules: resolveApp('node_modules'),
publicUrl: getPublicUrl(resolveApp('package.json')),
servedPath: getServedPath(resolveApp('package.json')),
// These properties only exist before ejecting:
ownPath: resolveOwn('.'),
ownNodeModules: resolveOwn('node_modules'), // This is empty on npm 3
};
const ownPackageJson = require('../package.json');
const reactScriptsPath = resolveApp(`node_modules/${ownPackageJson.name}`);
const reactScriptsLinked =
fs.existsSync(reactScriptsPath) &&
fs.lstatSync(reactScriptsPath).isSymbolicLink();
// config before publish: we're in ./packages/react-scripts/config/
if (
!reactScriptsLinked &&
__dirname.indexOf(path.join('packages', 'react-scripts', 'config')) !== -1
) {
module.exports = {
dotenv: resolveOwn('template/.env'),
appPath: resolveApp('.'),
appBuild: resolveOwn('../../build'),
appPublic: resolveOwn('template/public'),
appHtml: resolveOwn('template/public/index.html'),
appIndexJs: resolveOwn('template/src/index.js'),
appPackageJson: resolveOwn('package.json'),
appSrc: resolveOwn('template/src'),
yarnLockFile: resolveOwn('template/yarn.lock'),
testsSetup: resolveOwn('template/src/setupTests.js'),
appNodeModules: resolveOwn('node_modules'),
publicUrl: getPublicUrl(resolveOwn('package.json')),
servedPath: getServedPath(resolveOwn('package.json')),
// These properties only exist before ejecting:
ownPath: resolveOwn('.'),
ownNodeModules: resolveOwn('node_modules'),
};
}
// @remove-on-eject-end
// webpack-config-dev.js
'use strict';
const autoprefixer = require('autoprefixer');
const path = require('path');
const webpack = require('webpack'); //各种webpack配置
const HtmlWebpackPlugin = require('html-webpack-plugin');
const CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin');
const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
const WatchMissingNodeModulesPlugin = require('react-dev-utils/WatchMissingNodeModulesPlugin');
const eslintFormatter = require('react-dev-utils/eslintFormatter');
const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
const getClientEnvironment = require('./env');
const paths = require('./paths');
// Webpack uses `publicPath` to determine where the app is being served from.
// In development, we always serve from the root. This makes config easier.
const publicPath = '/';
const env = getClientEnvironment(publicUrl);
module.exports = { // 相关配置
devtool: 'cheap-module-source-map',
entry: [
// We ship a few polyfills by default:
require.resolve('./polyfills'),
require.resolve('react-dev-utils/webpackHotDevClient'),
// Finally, this is your app's code:
paths.appIndexJs
],
output: {
// Add /* filename */ comments to generated require()s in the output.
pathinfo: true,
// This does not produce a real file. It's just the virtual path that is
// served by WebpackDevServer in development. This is the JS bundle
// containing code from all our entry points, and the Webpack runtime.
filename: 'static/js/bundle.js',
// There are also additional JS chunk files if you use code splitting.
chunkFilename: 'static/js/[name].chunk.js',
// This is the URL that app is served from. We use "/" in development.
publicPath: publicPath,
// Point sourcemap entries to original disk location (format as URL on Windows)
devtoolModuleFilenameTemplate: info =>
path.resolve(info.absoluteResourcePath).replace(/\\/g, '/'),
},
resolve: {
// This allows you to set a fallback for where Webpack should look for modules.
// We placed these paths second because we want `node_modules` to "win"
// if there are any conflicts. This matches Node resolution mechanism.
// https://github.com/facebookincubator/create-react-app/issues/253
modules: ['node_modules', paths.appNodeModules].concat(
// It is guaranteed to exist because we tweak it in `env.js`
process.env.NODE_PATH.split(path.delimiter).filter(Boolean)
),
// These are the reasonable defaults supported by the Node ecosystem.
// We also include JSX as a common component filename extension to support
// some tools, although we do not recommend using it, see:
// https://github.com/facebookincubator/create-react-app/issues/290
// `web` extension prefixes have been added for better support
// for React Native Web.
extensions: ['.web.js', '.mjs', '.js', '.json', '.web.jsx', '.jsx'],
alias: {
// @remove-on-eject-begin
// Resolve Babel runtime relative to react-scripts.
// It usually still works on npm 3 without this but it would be
// unfortunate to rely on, as react-scripts could be symlinked,
// and thus babel-runtime might not be resolvable from the source.
'babel-runtime': path.dirname(
require.resolve('babel-runtime/package.json')
),
// @remove-on-eject-end
// Support React Native Web
// https://www.smashingmagazine.com/2016/08/a-glimpse-into-the-future-with-react-native-for-web/
'react-native': 'react-native-web',
},
plugins: [
// Prevents users from importing files from outside of src/ (or node_modules/).
// This often causes confusion because we only process files within src/ with babel.
// To fix this, we prevent you from importing files out of src/ -- if you'd like to,
// please link the files into your node_modules/ and let module-resolution kick in.
// Make sure your source files are compiled, as they will not be processed in any way.
new ModuleScopePlugin(paths.appSrc, [paths.appPackageJson]),
],
},
module: {
strictExportPresence: true,
rules: [
// TODO: Disable require.ensure as it's not a standard language feature.
// We are waiting for https://github.com/facebookincubator/create-react-app/issues/2176.
// { parser: { requireEnsure: false } },
// First, run the linter.
// It's important to do this before Babel processes the JS.
{
test: /\.(js|jsx|mjs)$/,
enforce: 'pre',
use: [
{
options: {
formatter: eslintFormatter,
eslintPath: require.resolve('eslint'),
// @remove-on-eject-begin
baseConfig: {
extends: [require.resolve('eslint-config-react-app')],
},
ignore: false,
useEslintrc: false,
// @remove-on-eject-end
},
loader: require.resolve('eslint-loader'),
},
],
include: paths.appSrc,
},
{
// "oneOf" will traverse all following loaders until one will
// match the requirements. When no loader matches it will fall
// back to the "file" loader at the end of the loader list.
oneOf: [
// "url" loader works like "file" loader except that it embeds assets
// smaller than specified limit in bytes as data URLs to avoid requests.
// A missing `test` is equivalent to a match.
{
test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
loader: require.resolve('url-loader'),
options: {
limit: 10000,
name: 'static/media/[name].[hash:8].[ext]',
},
},
// Process JS with Babel.
{
test: /\.(js|jsx|mjs)$/,
include: paths.appSrc,
loader: require.resolve('babel-loader'),
options: {
// @remove-on-eject-begin
babelrc: false,
presets: [require.resolve('babel-preset-react-app')],
// @remove-on-eject-end
// This is a feature of `babel-loader` for webpack (not Babel itself).
// It enables caching results in ./node_modules/.cache/babel-loader/
// directory for faster rebuilds.
cacheDirectory: true,
},
},
// "postcss" loader applies autoprefixer to our CSS.
// "css" loader resolves paths in CSS and adds assets as dependencies.
// "style" loader turns CSS into JS modules that inject <style> tags.
// In production, we use a plugin to extract that CSS to a file, but
// in development "style" loader enables hot editing of CSS.
{
test: /\.css$/,
use: [
require.resolve('style-loader'),
{
loader: require.resolve('css-loader'),
options: {
importLoaders: 1,
},
},
{
loader: require.resolve('postcss-loader'),
options: {
// Necessary for external CSS imports to work
// https://github.com/facebookincubator/create-react-app/issues/2677
ident: 'postcss',
plugins: () => [
require('postcss-flexbugs-fixes'),
autoprefixer({
browsers: [
'>1%',
'last 4 versions',
'Firefox ESR',
'not ie < 9', // React doesn't support IE8 anyway
],
flexbox: 'no-2009',
}),
],
},
},
],
},
// "file" loader makes sure those assets get served by WebpackDevServer.
// When you `import` an asset, you get its (virtual) filename.
// In production, they would get copied to the `build` folder.
// This loader doesn't use a "test" so it will catch all modules
// that fall through the other loaders.
{
// Exclude `js` files to keep "css" loader working as it injects
// its runtime that would otherwise processed through "file" loader.
// Also exclude `html` and `json` extensions so they get processed
// by webpacks internal loaders.
exclude: [/\.(js|jsx|mjs)$/, /\.html$/, /\.json$/],
loader: require.resolve('file-loader'),
options: {
name: 'static/media/[name].[hash:8].[ext]',
},
},
],
},
// ** STOP ** Are you adding a new loader?
// Make sure to add the new loader(s) before the "file" loader.
],
},
plugins: [
// Makes some environment variables available in index.html.
// The public URL is available as %PUBLIC_URL% in index.html, e.g.:
// <link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico">
// In development, this will be an empty string.
new InterpolateHtmlPlugin(env.raw),
// Generates an `index.html` file with the <script> injected.
new HtmlWebpackPlugin({
inject: true,
template: paths.appHtml,
}),
// Add module names to factory functions so they appear in browser profiler.
new webpack.NamedModulesPlugin(),
// Makes some environment variables available to the JS code, for example:
// if (process.env.NODE_ENV === 'development') { ... }. See `./env.js`.
new webpack.DefinePlugin(env.stringified),
// This is necessary to emit hot updates (currently CSS only):
new webpack.HotModuleReplacementPlugin(),
// Watcher doesn't work well if you mistype casing in a path so we use
// a plugin that prints an error when you attempt to do this.
// See https://github.com/facebookincubator/create-react-app/issues/240
new CaseSensitivePathsPlugin(),
// If you require a missing module and then `npm install` it, you still have
// to restart the development server for Webpack to discover it. This plugin
// makes the discovery automatic so you don't have to restart.
// See https://github.com/facebookincubator/create-react-app/issues/186
new WatchMissingNodeModulesPlugin(paths.appNodeModules),
// Moment.js is an extremely popular library that bundles large locale files
// by default due to how Webpack interprets its code. This is a practical
// solution that requires the user to opt into importing specific locales.
// https://github.com/jmblog/how-to-optimize-momentjs-with-webpack
// You can remove this if you don't use Moment.js:
new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/),
],
// Some libraries import Node modules but don't use them in the browser.
// Tell Webpack to provide empty mocks for them so importing them works.
node: {
dgram: 'empty',
fs: 'empty',
net: 'empty',
tls: 'empty',
child_process: 'empty',
},
// Turn off performance hints during development because we don't do any
// splitting or minification in interest of speed. These warnings become
// cumbersome.
performance: {
hints: false,
},
};
4、npm run eject命令
单向操作不可逆，npm eun eject命令暴露项目的配置，可以自由配置项目所需的依赖，不使用的版本零配置即可开发。
npm run eject后文件目录
npm run eject后package.json文件
执行npm run eject后，整个项目结构和配置和平时开发就没什么区别了。 30人点赞React
原文作者：芒果加奶，原文链接：https://www.jianshu.com/p/c6040430b18d
