我正在设置一个reactjs应用，并且包括一个本地库作为本地依赖项，例如：
module-lib: ../module-lib。
在此软件包中，我使用流程输入javascript。当我想编译我的react-app时，出现了这个错误：
./node_modules/module-lib/index.js
SyntaxError: /Users/.../module-test/node_modules/module-lib/index.js: Unexpected token, expected "," (2:17)
1 | //@flow
> 2 | export default (r: number): number => {
| ^
3 | return r * 2;
4 | };
5 |
我正试图告诉webpack使用流预置来转译库，但是它不起作用... 这是我的webpack.config.js：
const path = require("path");
const webpack = require("webpack");
const resolve = require("resolve");
const PnpWebpackPlugin = require("pnp-webpack-plugin");
const HtmlWebpackPlugin = require("html-webpack-plugin");
const CaseSensitivePathsPlugin = require("case-sensitive-paths-webpack-plugin");
const InlineChunkHtmlPlugin = require("react-dev-utils/InlineChunkHtmlPlugin");
const TerserPlugin = require("terser-webpack-plugin");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const OptimizeCSSAssetsPlugin = require("optimize-css-assets-webpack-plugin");
const safePostCssParser = require("postcss-safe-parser");
const ManifestPlugin = require("webpack-manifest-plugin");
const InterpolateHtmlPlugin = require("react-dev-utils/InterpolateHtmlPlugin");
const WorkboxWebpackPlugin = require("workbox-webpack-plugin");
const WatchMissingNodeModulesPlugin = require("react-dev-utils/WatchMissingNodeModulesPlugin");
const ModuleScopePlugin = require("react-dev-utils/ModuleScopePlugin");
const getCSSModuleLocalIdent = require("react-dev-utils/getCSSModuleLocalIdent");
const paths = require("./paths");
const getClientEnvironment = require("./env");
const ModuleNotFoundPlugin = require("react-dev-utils/ModuleNotFoundPlugin");
const ForkTsCheckerWebpackPlugin = require("fork-ts-checker-webpack-plugin-alt");
const typescriptFormatter = require("react-dev-utils/typescriptFormatter");
// Source maps are resource heavy and can cause out of memory issue for large source files.
const shouldUseSourceMap = process.env.GENERATE_SOURCEMAP !== "false";
// Some apps do not need the benefits of saving a web request, so not inlining the chunk
// makes for a smoother build process.
const shouldInlineRuntimeChunk = process.env.INLINE_RUNTIME_CHUNK !== "false";
// Check if TypeScript is setup
const useTypeScript = fs.existsSync(paths.appTsConfig);
// style files regexes
const cssRegex = /\.css$/;
const cssModuleRegex = /\.module\.css$/;
const sassRegex = /\.(scss|sass)$/;
const sassModuleRegex = /\.module\.(scss|sass)$/;
// This is the production and development configuration.
// It is focused on developer experience, fast rebuilds, and a minimal bundle.
module.exports = function(webpackEnv) {
const isEnvDevelopment = webpackEnv === "development";
const isEnvProduction = webpackEnv === "production";
// Webpack uses `publicPath` to determine where the app is being served from.
// It requires a trailing slash, or the file assets will get an incorrect path.
// In development, we always serve from the root. This makes config easier.
const publicPath = isEnvProduction
? paths.servedPath
: isEnvDevelopment && "/";
// Some apps do not use client-side routing with pushState.
// For these, "homepage" can be set to "." to enable relative asset paths.
const shouldUseRelativeAssetPaths = publicPath === "./";
// `publicUrl` is just like `publicPath`, but we will provide it to our app
// as %PUBLIC_URL% in `index.html` and `process.env.PUBLIC_URL` in JavaScript.
// Omit trailing slash as %PUBLIC_URL%/xyz looks better than %PUBLIC_URL%xyz.
const publicUrl = isEnvProduction
? publicPath.slice(0, -1)
: isEnvDevelopment && "";
// Get environment variables to inject into our app.
const env = getClientEnvironment(publicUrl);
// common function to get style loaders
const getStyleLoaders = (cssOptions, preProcessor) => {
const loaders = [
isEnvDevelopment && require.resolve("style-loader"),
isEnvProduction && {
loader: MiniCssExtractPlugin.loader,
options: Object.assign(
{},
shouldUseRelativeAssetPaths ? { publicPath: "../../" } : undefined
)
},
{
loader: require.resolve("css-loader"),
options: cssOptions
},
{
// Options for PostCSS as we reference these options twice
// Adds vendor prefixing based on your specified browser support in
// package.json
loader: require.resolve("postcss-loader"),
options: {
// Necessary for external CSS imports to work
// https://github.com/facebook/create-react-app/issues/2677
ident: "postcss",
plugins: () => [
require("postcss-flexbugs-fixes"),
require("postcss-preset-env")({
autoprefixer: {
flexbox: "no-2009"
},
stage: 3
})
],
sourceMap: isEnvProduction && shouldUseSourceMap
}
}
].filter(Boolean);
if (preProcessor) {
loaders.push({
loader: require.resolve(preProcessor),
options: {
sourceMap: isEnvProduction && shouldUseSourceMap
}
});
}
return loaders;
};
return {
mode: isEnvProduction ? "production" : isEnvDevelopment && "development",
// Stop compilation early in production
bail: isEnvProduction,
devtool: isEnvProduction
? shouldUseSourceMap
? "source-map"
: false
: isEnvDevelopment && "cheap-module-source-map",
// These are the "entry points" to our application.
// This means they will be the "root" imports that are included in JS bundle.
entry: [
// Include an alternative client for WebpackDevServer. A client's job is to
// connect to WebpackDevServer by a socket and get notified about changes.
// When you save a file, the client will either apply hot updates (in case
// of CSS changes), or refresh the page (in case of JS changes). When you
// make a syntax error, this client will display a syntax error overlay.
// Note: instead of the default WebpackDevServer client, we use a custom one
// to bring better experience for Create React App users. You can replace
// the line below with these two lines if you prefer the stock client:
// require.resolve('webpack-dev-server/client') + '?/',
// require.resolve('webpack/hot/dev-server'),
isEnvDevelopment &&
require.resolve("react-dev-utils/webpackHotDevClient"),
// Finally, this is your app's code:
paths.appIndexJs
// We include the app code last so that if there is a runtime error during
// initialization, it doesn't blow up the WebpackDevServer client, and
// changing JS code would still trigger a refresh.
].filter(Boolean),
output: {
// The build folder.
path: isEnvProduction ? paths.appBuild : undefined,
// Add /* filename */ comments to generated require()s in the output.
pathinfo: isEnvDevelopment,
// There will be one main bundle, and one file per asynchronous chunk.
// In development, it does not produce real files.
filename: isEnvProduction
? "static/js/[name].[chunkhash:8].js"
: isEnvDevelopment && "static/js/bundle.js",
// There are also additional JS chunk files if you use code splitting.
chunkFilename: isEnvProduction
? "static/js/[name].[chunkhash:8].chunk.js"
: isEnvDevelopment && "static/js/[name].chunk.js",
// We inferred the "public path" (such as / or /my-project) from homepage.
// We use "/" in development.
publicPath: publicPath,
// Point sourcemap entries to original disk location (format as URL on Windows)
devtoolModuleFilenameTemplate: isEnvProduction
? info =>
path
.relative(paths.appSrc, info.absoluteResourcePath)
.replace(/\\/g, "/")
: isEnvDevelopment &&
(info => path.resolve(info.absoluteResourcePath).replace(/\\/g, "/"))
},
optimization: {
minimize: isEnvProduction,
minimizer: [
// This is only used in production mode
new TerserPlugin({
terserOptions: {
parse: {
// we want terser to parse ecma 8 code. However, we don't want it
// to apply any minfication steps that turns valid ecma 5 code
// into invalid ecma 5 code. This is why the 'compress' and 'output'
// sections only apply transformations that are ecma 5 safe
// https://github.com/facebook/create-react-app/pull/4234
ecma: 8
},
compress: {
ecma: 5,
warnings: false,
// Disabled because of an issue with Uglify breaking seemingly valid code:
// https://github.com/facebook/create-react-app/issues/2376
// Pending further investigation:
// https://github.com/mishoo/UglifyJS2/issues/2011
comparisons: false,
// Disabled because of an issue with Terser breaking valid code:
// https://github.com/facebook/create-react-app/issues/5250
// Pending futher investigation:
// https://github.com/terser-js/terser/issues/120
inline: 2
},
mangle: {
safari10: true
},
output: {
ecma: 5,
comments: false,
// Turned on because emoji and regex is not minified properly using default
// https://github.com/facebook/create-react-app/issues/2488
ascii_only: true
}
},
// Use multi-process parallel running to improve the build speed
// Default number of concurrent runs: os.cpus().length - 1
parallel: true,
// Enable file caching
cache: true,
sourceMap: shouldUseSourceMap
}),
// This is only used in production mode
new OptimizeCSSAssetsPlugin({
cssProcessorOptions: {
parser: safePostCssParser,
map: shouldUseSourceMap
? {
// `inline: false` forces the sourcemap to be output into a
// separate file
inline: false,
// `annotation: true` appends the sourceMappingURL to the end of
// the css file, helping the browser find the sourcemap
annotation: true
}
: false
}
})
],
// Automatically split vendor and commons
// https://twitter.com/wSokra/status/969633336732905474
// https://medium.com/webpack/webpack-4-code-splitting-chunk-graph-and-the-splitchunks-optimization-be739a861366
splitChunks: {
chunks: "all",
name: false
},
// Keep the runtime chunk separated to enable long term caching
// https://twitter.com/wSokra/status/969679223278505985
runtimeChunk: true
},
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/facebook/create-react-app/issues/253
modules: ["node_modules"].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/facebook/create-react-app/issues/290
// `web` extension prefixes have been added for better support
// for React Native Web.
extensions: paths.moduleFileExtensions
.map(ext => `.${ext}`)
.filter(ext => useTypeScript || !ext.includes("ts")),
alias: {
// Support React Native Web
// https://www.smashingmagazine.com/2016/08/a-glimpse-into-the-future-with-react-native-for-web/
"react-native": "react-native-web"
},
plugins: [
// Adds support for installing with Plug'n'Play, leading to faster installs and adding
// guards against forgotten dependencies and such.
PnpWebpackPlugin,
// Prevents users from importing files from outside of src/ (or node_modules/).
// This often causes confusion because we only process files within src/ with babel.
// To fix this, we prevent you from importing files out of src/ -- if you'd like to,
// please link the files into your node_modules/ and let module-resolution kick in.
// Make sure your source files are compiled, as they will not be processed in any way.
new ModuleScopePlugin(paths.appSrc, [paths.appPackageJson])
]
},
resolveLoader: {
plugins: [
// Also related to Plug'n'Play, but this time it tells Webpack to load its loaders
// from the current package.
PnpWebpackPlugin.moduleLoader(module)
]
},
module: {
strictExportPresence: true,
rules: [
// Disable require.ensure as it's not a standard language feature.
{ parser: { requireEnsure: false } },
// First, run the linter.
// It's important to do this before Babel processes the JS.
{
test: /\.(js|mjs|jsx)$/,
enforce: "pre",
use: [
{
options: {
formatter: require.resolve("react-dev-utils/eslintFormatter"),
eslintPath: require.resolve("eslint")
},
loader: require.resolve("eslint-loader")
}
],
include: [paths.appSrc, paths.moduleLib]
},
{
// "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 application JS with Babel.
// The preset includes JSX, Flow, TypeScript, and some ESnext features.
{
test: /\.(js|mjs|jsx|ts|tsx)$/,
include: [paths.appSrc, paths.moduleLib],
loader: require.resolve("babel-loader"),
options: {
customize: require.resolve(
"babel-preset-react-app/webpack-overrides"
),
plugins: [
[
require.resolve("babel-plugin-named-asset-import"),
{
loaderMap: {
svg: {
ReactComponent: "@svgr/webpack?-prettier,-svgo![path]"
}
}
}
]
],
// This is a feature of `babel-loader` for webpack (not Babel itself).
// It enables caching results in ./node_modules/.cache/babel-loader/
// directory for faster rebuilds.
cacheDirectory: false,
cacheCompression: isEnvProduction,
compact: isEnvProduction
}
},
// Process any JS outside of the app with Babel.
// Unlike the application JS, we only compile the standard ES features.
{
test: /\.(js|mjs)$/,
exclude: /@babel(?:\/|\\{1,2})runtime/,
loader: require.resolve("babel-loader"),
options: {
babelrc: false,
configFile: false,
compact: false,
presets: [
[
require.resolve("babel-preset-react-app/dependencies"),
{ helpers: true }
]
],
cacheDirectory: false,
cacheCompression: isEnvProduction,
// If an error happens in a package, it's possible to be
// because it was compiled. Thus, we don't want the browser
// debugger to show the original code. Instead, the code
// being evaluated would be much more helpful.
sourceMaps: false
}
},
// "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 MiniCSSExtractPlugin to extract that CSS
// to a file, but in development "style" loader enables hot editing
// of CSS.
// By default we support CSS Modules with the extension .module.css
{
test: cssRegex,
exclude: cssModuleRegex,
use: getStyleLoaders({
importLoaders: 1,
sourceMap: isEnvProduction && shouldUseSourceMap
}),
// Don't consider CSS imports dead code even if the
// containing package claims to have no side effects.
// Remove this when webpack adds a warning or an error for this.
// See https://github.com/webpack/webpack/issues/6571
sideEffects: true
},
// Adds support for CSS Modules (https://github.com/css-modules/css-modules)
// using the extension .module.css
{
test: cssModuleRegex,
use: getStyleLoaders({
importLoaders: 1,
sourceMap: isEnvProduction && shouldUseSourceMap,
modules: true,
getLocalIdent: getCSSModuleLocalIdent
})
},
// Opt-in support for SASS (using .scss or .sass extensions).
// By default we support SASS Modules with the
// extensions .module.scss or .module.sass
{
test: sassRegex,
exclude: sassModuleRegex,
use: getStyleLoaders(
{
importLoaders: 2,
sourceMap: isEnvProduction && shouldUseSourceMap
},
"sass-loader"
),
// Don't consider CSS imports dead code even if the
// containing package claims to have no side effects.
// Remove this when webpack adds a warning or an error for this.
// See https://github.com/webpack/webpack/issues/6571
sideEffects: true
},
// Adds support for CSS Modules, but using SASS
// using the extension .module.scss or .module.sass
{
test: sassModuleRegex,
use: getStyleLoaders(
{
importLoaders: 2,
sourceMap: isEnvProduction && shouldUseSourceMap,
modules: true,
getLocalIdent: getCSSModuleLocalIdent
},
"sass-loader"
)
},
exclude: [/\.(js|mjs|jsx|ts|tsx)$/, /\.html$/, /\.json$/],
options: {
name: "static/media/[name].[hash:8].[ext]"
}
}
]
}
]
},
plugins: [
new HtmlWebpackPlugin(
Object.assign(
{},
{
inject: true,
template: paths.appHtml
},
isEnvProduction
? {
minify: {
removeComments: true,
collapseWhitespace: true,
removeRedundantAttributes: true,
useShortDoctype: true,
removeEmptyAttributes: true,
removeStyleLinkTypeAttributes: true,
keepClosingSlash: true,
minifyJS: true,
minifyCSS: true,
minifyURLs: true
}
}
: undefined
)
),
isEnvProduction &&
shouldInlineRuntimeChunk &&
new InlineChunkHtmlPlugin(HtmlWebpackPlugin, [/runtime~.+[.]js/]),
new webpack.DefinePlugin(env.stringified),
isEnvDevelopment && new webpack.HotModuleReplacementPlugin(),
isEnvDevelopment &&
new WatchMissingNodeModulesPlugin(paths.appNodeModules),
isEnvProduction &&
new MiniCssExtractPlugin({
filename: "static/css/[name].[contenthash:8].css",
chunkFilename: "static/css/[name].[contenthash:8].chunk.css"
}),
new ManifestPlugin({
fileName: "asset-manifest.json",
publicPath: publicPath
}),
isEnvProduction &&
new WorkboxWebpackPlugin.GenerateSW({
clientsClaim: true,
exclude: [/\.map$/, /asset-manifest\.json$/],
importWorkboxFrom: "cdn",
navigateFallback: publicUrl + "/index.html",
navigateFallbackBlacklist: [
new RegExp("^/_"),
new RegExp("/[^/]+\\.[^/]+$")
]
}),
useTypeScript &&
new ForkTsCheckerWebpackPlugin({
typescript: resolve.sync("typescript", {
basedir: paths.appNodeModules
}),
async: false,
checkSyntacticErrors: true,
tsconfig: paths.appTsConfig,
compilerOptions: {
module: "esnext",
moduleResolution: "node",
resolveJsonModule: true,
isolatedModules: true,
noEmit: true,
jsx: "preserve"
},
reportFiles: [
"**",
"!**/*.json",
"!**/__tests__/**",
"!**/?(*.)(spec|test).*",
"!**/src/setupProxy.*",
"!**/src/setupTests.*"
],
watch: [paths.appSrc],
silent: true,
formatter: typescriptFormatter
})
].filter(Boolean),
node: {
dgram: "empty",
fs: "empty",
net: "empty",
tls: "empty",
child_process: "empty"
},
performance: false
};
};