webpack-config.ts

import ForkTsCheckerWebpackPlugin from 'fork-ts-checker-webpack-plugin'
import fs from 'fs'
import {
  CLIENT_STATIC_FILES_RUNTIME_MAIN,
  CLIENT_STATIC_FILES_RUNTIME_WEBPACK,
  REACT_LOADABLE_MANIFEST,
  SERVER_DIRECTORY,
} from 'next-server/constants'
import resolve from 'next/dist/compiled/resolve/index.js'
import path from 'path'
import webpack from 'webpack'

import {
  DOT_NEXT_ALIAS,
  NEXT_PROJECT_ROOT,
  NEXT_PROJECT_ROOT_DIST_CLIENT,
  PAGES_DIR_ALIAS,
} from '../lib/constants'
import { fileExists } from '../lib/file-exists'
import { WebpackEntrypoints } from './entries'
import { AllModulesIdentifiedPlugin } from './webpack/plugins/all-modules-identified-plugin'
import BuildManifestPlugin from './webpack/plugins/build-manifest-plugin'
import { ChunkGraphPlugin } from './webpack/plugins/chunk-graph-plugin'
import ChunkNamesPlugin from './webpack/plugins/chunk-names-plugin'
import { importAutoDllPlugin } from './webpack/plugins/dll-import'
import { HashedChunkIdsPlugin } from './webpack/plugins/hashed-chunk-ids-plugin'
import { DropClientPage } from './webpack/plugins/next-drop-client-page-plugin'
import NextJsSsrImportPlugin from './webpack/plugins/nextjs-ssr-import'
import NextJsSSRModuleCachePlugin from './webpack/plugins/nextjs-ssr-module-cache'
import PagesManifestPlugin from './webpack/plugins/pages-manifest-plugin'
import { ReactLoadablePlugin } from './webpack/plugins/react-loadable-plugin'
import { ServerlessPlugin } from './webpack/plugins/serverless-plugin'
import { SharedRuntimePlugin } from './webpack/plugins/shared-runtime-plugin'
import { TerserPlugin } from './webpack/plugins/terser-webpack-plugin/src/index'

type ExcludesFalse = <T>(x: T | false) => x is T

export default async function getBaseWebpackConfig(
  dir: string,
  {
    dev = false,
    isServer = false,
    buildId,
    config,
    target = 'server',
    entrypoints,
    selectivePageBuilding = false,
  }: {
    dev?: boolean
    isServer?: boolean
    buildId: string
    config: any
    target?: string
    entrypoints: WebpackEntrypoints
    selectivePageBuilding?: boolean
  }
): Promise<webpack.Configuration> {
  const distDir = path.join(dir, config.distDir)
  const defaultLoaders = {
    babel: {
      loader: 'next-babel-loader',
      options: {
        isServer,
        distDir,
        cwd: dir,
        cache: !selectivePageBuilding,
        asyncToPromises: config.experimental.asyncToPromises,
      },
    },
    // Backwards compat
    hotSelfAccept: {
      loader: 'noop-loader',
    },
  }

  // Support for NODE_PATH
  const nodePathList = (process.env.NODE_PATH || '')
    .split(process.platform === 'win32' ? ';' : ':')
    .filter(p => !!p)

  const outputDir = target === 'serverless' ? 'serverless' : SERVER_DIRECTORY
  const outputPath = path.join(distDir, isServer ? outputDir : '')
  const totalPages = Object.keys(entrypoints).length
  const clientEntries = !isServer
    ? {
        // Backwards compatibility
        'main.js': [],
        [CLIENT_STATIC_FILES_RUNTIME_MAIN]:
          `.${path.sep}` +
          path.relative(
            dir,
            path.join(
              NEXT_PROJECT_ROOT_DIST_CLIENT,
              dev ? `next-dev.js` : 'next.js'
            )
          ),
      }
    : undefined

  let typeScriptPath
  try {
    typeScriptPath = resolve.sync('typescript', { basedir: dir })
  } catch (_) {}
  const tsConfigPath = path.join(dir, 'tsconfig.json')
  const useTypeScript = Boolean(
    typeScriptPath && (await fileExists(tsConfigPath))
  )

  const resolveConfig = {
    // Disable .mjs for node_modules bundling
    extensions: isServer
      ? [
          ...(useTypeScript ? ['.tsx', '.ts'] : []),
          '.js',
          '.mjs',
          '.jsx',
          '.json',
          '.wasm',
        ]
      : [
          ...(useTypeScript ? ['.tsx', '.ts'] : []),
          '.mjs',
          '.js',
          '.jsx',
          '.json',
          '.wasm',
        ],
    modules: [
      'node_modules',
      ...nodePathList, // Support for NODE_PATH environment variable
    ],
    alias: {
      // These aliases make sure the wrapper module is not included in the bundles
      // Which makes bundles slightly smaller, but also skips parsing a module that we know will result in this alias
      'next/head': 'next-server/dist/lib/head.js',
      'next/router': 'next/dist/client/router.js',
      'next/config': 'next-server/dist/lib/runtime-config.js',
      'next/dynamic': 'next-server/dist/lib/dynamic.js',
      next: NEXT_PROJECT_ROOT,
      [PAGES_DIR_ALIAS]: path.join(dir, 'pages'),
      [DOT_NEXT_ALIAS]: distDir,
    },
    mainFields: isServer ? ['main', 'module'] : ['browser', 'module', 'main'],
  }

  const webpackMode = dev ? 'development' : 'production'

  const terserPluginConfig = {
    parallel: true,
    sourceMap: false,
    cache: !selectivePageBuilding,
    cpus: config.experimental.cpus,
    distDir: distDir,
  }
  const terserOptions = {
    parse: {
      ecma: 8,
    },
    compress: {
      ecma: 5,
      warnings: false,
      // The following two options are known to break valid JavaScript code
      comparisons: false,
      inline: 2, // https://github.com/zeit/next.js/issues/7178#issuecomment-493048965
    },
    mangle: { safari10: true },
    output: {
      ecma: 5,
      safari10: true,
      comments: false,
      // Fixes usage of Emoji and certain Regex
      ascii_only: true,
    },
  }

  const devtool = dev ? 'cheap-module-source-map' : false

  let webpackConfig: webpack.Configuration = {
    devtool,
    mode: webpackMode,
    name: isServer ? 'server' : 'client',
    target: isServer ? 'node' : 'web',
    externals: !isServer
      ? undefined
      : target !== 'serverless'
      ? [
          (context, request, callback) => {
            const notExternalModules = [
              'next/app',
              'next/document',
              'next/link',
              'next/error',
              'string-hash',
              'next/constants',
            ]

            if (notExternalModules.indexOf(request) !== -1) {
              return callback()
            }

            resolve(
              request,
              { basedir: dir, preserveSymlinks: true },
              (err, res) => {
                if (err) {
                  return callback()
                }

                if (!res) {
                  return callback()
                }

                // Default pages have to be transpiled
                if (
                  res.match(/next[/\\]dist[/\\]/) ||
                  res.match(/node_modules[/\\]@babel[/\\]runtime[/\\]/) ||
                  res.match(/node_modules[/\\]@babel[/\\]runtime-corejs2[/\\]/)
                ) {
                  return callback()
                }

                // Webpack itself has to be compiled because it doesn't always use module relative paths
                if (
                  res.match(/node_modules[/\\]webpack/) ||
                  res.match(/node_modules[/\\]css-loader/)
                ) {
                  return callback()
                }

                if (res.match(/node_modules[/\\].*\.js$/)) {
                  return callback(undefined, `commonjs ${request}`)
                }

                callback()
              }
            )
          },
        ]
      : [
          // When the serverless target is used all node_modules will be compiled into the output bundles
          // So that the serverless bundles have 0 runtime dependencies
          'amp-toolbox-optimizer', // except this one
          (context, request, callback) => {
            if (
              request === 'react-ssr-prepass' &&
              !config.experimental.ampBindInitData
            ) {
              // if it's the Next.js' require mark it as external
              // since it's not used
              if (
                context.replace(/\\/g, '/').includes('next-server/dist/server')
              ) {
                return callback(undefined, `commonjs ${request}`)
              }
            }
            return callback()
          },
        ],
    optimization: Object.assign(
      {
        checkWasmTypes: false,
        nodeEnv: false,
      },
      isServer
        ? {
            splitChunks: false,
            minimize: false,
          }
        : {
            runtimeChunk: selectivePageBuilding
              ? false
              : {
                  name: CLIENT_STATIC_FILES_RUNTIME_WEBPACK,
                },
            splitChunks: dev
              ? {
                  cacheGroups: {
                    default: false,
                    vendors: false,
                  },
                }
              : selectivePageBuilding
              ? {
                  cacheGroups: {
                    default: false,
                    vendors: false,
                    react: {
                      name: 'commons',
                      chunks: 'all',
                      test: /[\\/]node_modules[\\/](react|react-dom)[\\/]/,
                    },
                  },
                }
              : {
                  chunks: 'all',
                  cacheGroups: {
                    default: false,
                    vendors: false,
                    commons: {
                      name: 'commons',
                      chunks: 'all',
                      minChunks: totalPages > 2 ? totalPages * 0.5 : 2,
                    },
                    react: {
                      name: 'commons',
                      chunks: 'all',
                      test: /[\\/]node_modules[\\/](react|react-dom)[\\/]/,
                    },
                  },
                },
            minimize: !dev,
            minimizer: !dev
              ? [
                  new TerserPlugin({
                    ...terserPluginConfig,
                    terserOptions: {
                      ...terserOptions,
                      // Disable compress when using terser loader
                      ...(selectivePageBuilding ||
                      config.experimental.terserLoader
                        ? { compress: false }
                        : undefined),
                    },
                  }),
                ]
              : undefined,
          },
      selectivePageBuilding
        ? {
            providedExports: false,
            usedExports: false,
            concatenateModules: false,
          }
        : undefined
    ),
    recordsPath: selectivePageBuilding
      ? undefined
      : path.join(outputPath, 'records.json'),
    context: dir,
    // Kept as function to be backwards compatible
    entry: async () => {
      return {
        ...(clientEntries ? clientEntries : {}),
        ...entrypoints,
      }
    },
    output: {
      path: outputPath,
      filename: ({ chunk }: { chunk: { name: string } }) => {
        // Use `[name]-[contenthash].js` in production
        if (
          !dev &&
          (chunk.name === CLIENT_STATIC_FILES_RUNTIME_MAIN ||
            chunk.name === CLIENT_STATIC_FILES_RUNTIME_WEBPACK)
        ) {
          return chunk.name.replace(/\.js$/, '-[contenthash].js')
        }
        return '[name]'
      },
      libraryTarget: isServer ? 'commonjs2' : 'var',
      hotUpdateChunkFilename: 'static/webpack/[id].[hash].hot-update.js',
      hotUpdateMainFilename: 'static/webpack/[hash].hot-update.json',
      // This saves chunks with the name given via `import()`
      chunkFilename: isServer
        ? `${dev ? '[name]' : '[name].[contenthash]'}.js`
        : `static/chunks/${dev ? '[name]' : '[name].[contenthash]'}.js`,
      strictModuleExceptionHandling: true,
      crossOriginLoading: config.crossOrigin,
      futureEmitAssets: !dev,
      webassemblyModuleFilename: 'static/wasm/[modulehash].wasm',
    },
    performance: false,
    resolve: resolveConfig,
    resolveLoader: {
      modules: [
        path.join(__dirname, 'webpack', 'loaders'), // The loaders Next.js provides
        'node_modules',
        ...nodePathList, // Support for NODE_PATH environment variable
      ],
    },
    // @ts-ignore this is filtered
    module: {
      strictExportPresence: true,
      rules: [
        (selectivePageBuilding || config.experimental.terserLoader) &&
          !isServer && {
            test: /\.(js|mjs|jsx)$/,
            exclude: /\.min\.(js|mjs|jsx)$/,
            use: {
              loader: 'next-minify-loader',
              options: {
                terserOptions: {
                  ...terserOptions,
                  mangle: false,
                },
              },
            },
          },
        config.experimental.ampBindInitData &&
          !isServer && {
            test: /\.(tsx|ts|js|mjs|jsx)$/,
            include: [path.join(dir, 'data')],
            use: 'next-data-loader',
          },
        {
          test: /\.(tsx|ts|js|mjs|jsx)$/,
          include: [
            dir,
            /next-server[\\/]dist[\\/]lib/,
            /next[\\/]dist[\\/]client/,
            /next[\\/]dist[\\/]pages/,
            /[\\/](strip-ansi|ansi-regex)[\\/]/,
          ],
          exclude: (path: string) => {
            if (
              /next-server[\\/]dist[\\/]lib/.test(path) ||
              /next[\\/]dist[\\/]client/.test(path) ||
              /next[\\/]dist[\\/]pages/.test(path) ||
              /[\\/](strip-ansi|ansi-regex)[\\/]/.test(path)
            ) {
              return false
            }

            return /node_modules/.test(path)
          },
          use: defaultLoaders.babel,
        },
      ].filter(Boolean),
    },
    plugins: [
      // This plugin makes sure `output.filename` is used for entry chunks
      new ChunkNamesPlugin(),
      new webpack.DefinePlugin({
        ...Object.keys(config.env).reduce((acc, key) => {
          if (/^(?:NODE_.+)|(?:__.+)$/i.test(key)) {
            throw new Error(
              `The key "${key}" under "env" in next.config.js is not allowed. https://err.sh/zeit/next.js/env-key-not-allowed`
            )
          }

          return {
            ...acc,
            [`process.env.${key}`]: JSON.stringify(config.env[key]),
          }
        }, {}),
        'process.env.NODE_ENV': JSON.stringify(webpackMode),
        'process.crossOrigin': JSON.stringify(config.crossOrigin),
        'process.browser': JSON.stringify(!isServer),
        // This is used in client/dev-error-overlay/hot-dev-client.js to replace the dist directory
        ...(dev && !isServer
          ? {
              'process.env.__NEXT_DIST_DIR': JSON.stringify(distDir),
            }
          : {}),
        'process.env.__NEXT_EXPORT_TRAILING_SLASH': JSON.stringify(
          config.exportTrailingSlash
        ),
        ...(isServer
          ? {
              // Allow browser-only code to be eliminated
              'typeof window': JSON.stringify('undefined'),
              // Fix bad-actors in the npm ecosystem (e.g. `node-formidable`)
              // This is typically found in unmaintained modules from the
              // pre-webpack era (common in server-side code)
              'global.GENTLY': JSON.stringify(false),
            }
          : {
              // Allow server-only code to be eliminated
              'typeof window': JSON.stringify('object'),
            }),
      }),
      !isServer &&
        new ReactLoadablePlugin({
          filename: REACT_LOADABLE_MANIFEST,
        }),
      !isServer && new DropClientPage(),
      new ChunkGraphPlugin(buildId, {
        dir,
        distDir,
        isServer,
      }),
      ...(dev
        ? (() => {
            // Even though require.cache is server only we have to clear assets from both compilations
            // This is because the client compilation generates the build manifest that's used on the server side
            const {
              NextJsRequireCacheHotReloader,
            } = require('./webpack/plugins/nextjs-require-cache-hot-reloader')
            const {
              UnlinkRemovedPagesPlugin,
            } = require('./webpack/plugins/unlink-removed-pages-plugin')
            const devPlugins = [
              new UnlinkRemovedPagesPlugin(),
              new webpack.NoEmitOnErrorsPlugin(),
              new NextJsRequireCacheHotReloader(),
            ]

            if (!isServer) {
              const AutoDllPlugin = importAutoDllPlugin({ distDir })
              devPlugins.push(
                new AutoDllPlugin({
                  filename: '[name]_[hash].js',
                  path: './static/development/dll',
                  context: dir,
                  entry: {
                    dll: ['react', 'react-dom'],
                  },
                  config: {
                    devtool,
                    mode: webpackMode,
                    resolve: resolveConfig,
                  },
                })
              )
              devPlugins.push(new webpack.HotModuleReplacementPlugin())
            }

            return devPlugins
          })()
        : []),
      !dev && new webpack.HashedModuleIdsPlugin(),
      // This must come after HashedModuleIdsPlugin (it sets any modules that
      // were missed by HashedModuleIdsPlugin)
      !dev && selectivePageBuilding && new AllModulesIdentifiedPlugin(dir),
      // This sets chunk ids to be hashed versions of their names to reduce
      // bundle churn
      !dev && selectivePageBuilding && new HashedChunkIdsPlugin(buildId),
      // On the client we want to share the same runtime cache
      !isServer && selectivePageBuilding && new SharedRuntimePlugin(),
      !dev &&
        new webpack.IgnorePlugin({
          checkResource: (resource: string) => {
            return /react-is/.test(resource)
          },
          checkContext: (context: string) => {
            return (
              /next-server[\\/]dist[\\/]/.test(context) ||
              /next[\\/]dist[\\/]/.test(context)
            )
          },
        }),
      target === 'serverless' &&
        (isServer || selectivePageBuilding) &&
        new ServerlessPlugin(buildId, { isServer }),
      isServer && new PagesManifestPlugin(target === 'serverless'),
      target !== 'serverless' &&
        isServer &&
        new NextJsSSRModuleCachePlugin({ outputPath }),
      isServer && new NextJsSsrImportPlugin(),
      !isServer && new BuildManifestPlugin(),
      config.experimental.profiling &&
        new webpack.debug.ProfilingPlugin({
          outputPath: path.join(
            distDir,
            `profile-events-${isServer ? 'server' : 'client'}.json`
          ),
        }),
      !isServer &&
        useTypeScript &&
        new ForkTsCheckerWebpackPlugin({
          typescript: typeScriptPath,
          async: dev,
          useTypescriptIncrementalApi: true,
          checkSyntacticErrors: true,
          tsconfig: tsConfigPath,
          reportFiles: ['**', '!**/__tests__/**', '!**/?(*.)(spec|test).*'],
          compilerOptions: { isolatedModules: true, noEmit: true },
          silent: true,
          formatter: 'codeframe',
        }),
    ].filter((Boolean as any) as ExcludesFalse),
  }

  if (typeof config.webpack === 'function') {
    webpackConfig = config.webpack(webpackConfig, {
      dir,
      dev,
      isServer,
      buildId,
      config,
      defaultLoaders,
      totalPages,
      webpack,
    })

    // @ts-ignore: Property 'then' does not exist on type 'Configuration'
    if (typeof webpackConfig.then === 'function') {
      console.warn(
        '> Promise returned in next config. https://err.sh/zeit/next.js/promise-in-next-config.md'
      )
    }
  }

  // check if using @zeit/next-typescript and show warning
  if (
    isServer &&
    webpackConfig.module &&
    Array.isArray(webpackConfig.module.rules)
  ) {
    let foundTsRule = false

    webpackConfig.module.rules = webpackConfig.module.rules.filter(
      (rule): boolean => {
        if (!(rule.test instanceof RegExp)) return true
        if ('noop.ts'.match(rule.test) && !'noop.js'.match(rule.test)) {
          // remove if it matches @zeit/next-typescript
          foundTsRule = rule.use === defaultLoaders.babel
          return !foundTsRule
        }
        return true
      }
    )

    if (foundTsRule) {
      console.warn(
        '\n@zeit/next-typescript is no longer needed since Next.js has built-in support for TypeScript now. Please remove it from your next.config.js\n'
      )
    }
  }

  // Backwards compat for `main.js` entry key
  const originalEntry: any = webpackConfig.entry
  if (typeof originalEntry !== 'undefined') {
    webpackConfig.entry = async () => {
      const entry: WebpackEntrypoints =
        typeof originalEntry === 'function'
          ? await originalEntry()
          : originalEntry
      // Server compilation doesn't have main.js
      if (clientEntries && entry['main.js'] && entry['main.js'].length > 0) {
        const originalFile = clientEntries[CLIENT_STATIC_FILES_RUNTIME_MAIN]
        entry[CLIENT_STATIC_FILES_RUNTIME_MAIN] = [
          ...entry['main.js'],
          originalFile,
        ]
      }
      delete entry['main.js']

      return entry
    }
  }

  if (!dev) {
    // @ts-ignore entry is always a function
    webpackConfig.entry = await webpackConfig.entry()
  }

  return webpackConfig
}