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webpack5-localization-plugin

README.md

@rushstack/webpack5-localization-plugin

Installation

npm install @rushstack/webpack5-localization-plugin --save-dev

Overview

This Webpack plugin produces bundles that have multiple locales' variants of strings embedded. It also has out-of-box support for RESX files in addition to JSON strings files (with the extensions .loc.json or .resjson).

The loaders can also be chained with other loaders that convert the content to one of the known formats.

Plugin

To use the plugin, add it to the plugins array of your Webpack config, and specify one or more loaders. For example:

import { LocalizationPlugin } from '@rushstack/webpack5-localization-plugin';

{
  plugins: [
    new LocalizationPlugin( /* options */ )
  ],
  module: {
    rules: [{
      test: /\.resjson$/,
      use: {
        // All loaders are available in `@rushstack/webpack5-localization-plugin/lib/loaders/`
        // Loaders for specific formats: `resjson-loader`, `locjson-loader`, `resx-loader`
        // Loader that switches on file extension: `loc-loader`
        // Loader that switches on file extension and skips localization: `default-locale-loader`
        loader: require.resolve('@rushstack/webpack5-localization-plugin/lib/loaders/resjson-loader')
      },
      // Can be one of `javascript/esm`, `javascript/dynamic`, or `json`
      // `javascript/esm` will produce the smallest bundle sizes, while `json` will produce faster code for large string tables
      type: 'javascript/esm',
      sideEffects: false
    }]
  }
}

A note about the dev server: When Webpack is being run by the Webpack dev server, this plugin pipes the strings in the loc files in the source (the .loc.json and the .resx files) to the output without any translations.

Options

localizedData = { }

localizedData.defaultLocale = { }

This option has a required property (localeName), to specify the name of the locale used in the .resx and .loc.json files in the source.

localizedData.defaultLocale.fillMissingTranslationStrings = true | false

If this option is set to true, strings that are missing from localizedData.translatedStrings will be provided by the default locale (the strings in the .resx and .loc.json files in the source). If this option is unset or set to false, an error will be emitted if a string is missing from localizedData.translatedStrings.

localizedData.translatedStrings = { }

This option is used to specify the localization data to be used in the build. This object has the following structure:

  • Locale name
    • Compilation context-relative or absolute localization file path
      • Translated strings

For example:

translatedStrings: {
  "en-us": {
    "./src/strings1.loc.json": {
      "string1": "the first string"
    }
  },
  "es-es": {
    "./src/strings1.loc.json": {
      "string1": "la primera cadena"
    }
  }
}

Alternatively, instead of directly specifying the translations, a path to a translated resource file can be specified. For example:

translatedStrings: {
  "en-us": {
    "./src/strings1.loc.json": "./localization/en-us/strings1.loc.json"
  },
  "es-es": {
    "./src/strings1.loc.json": "./localization/es-es/strings1.loc.json"
  }
}

localizedData.resolveMissingTranslatedStrings = (locales: string[], filePath: string, context: LoaderContext<{}>) => { ... }

This optional option can be used to resolve translated data that is missing from data that is provided in the localizedData.translatedStrings option. Set this option with a function expecting two parameters: the first, an array of locale names, and second, a fully-qualified path to the localized file in source. The function should synchronously or asynchronously (as a promise) return an object (or map) with locale names as keys and localized data as values. The localized data value should be one of:

  • a string: The absolute path to the translated data in .resx, .loc.json, or .resjson format
  • an object: An object containing the translated data
  • a map: A map containing the translated data

Note that these values are the same as the values that can be specified for translations for a localized resource in localizedData.translatedStrings.

If the function returns data that is missing locales or individual strings, the plugin will fall back to the default locale if localizedData.defaultLocale.fillMissingTranslationStrings is set to true. If localizedData.defaultLocale.fillMissingTranslationStrings is set to false, an error will result.

localizedData.passthroughLocale = { }

This option is used to specify how and if a passthrough locale should be generated. A passthrough locale is a generated locale in which each string's value is its name. This is useful for debugging and for identifying cases where a locale is missing.

This option takes two optional properties:

localizedData.passthroughLocale.usePassthroughLocale = true | false

If passthroughLocale.usePassthroughLocale is set to true, a passthrough locale will be included in the output. By default, the passthrough locale's name is "passthrough."

localizedData.passthroughLocale.passthroughLocaleName = '...'

If passthroughLocale.usePassthroughLocale is set to true, the "passthrough" locale name can be overridden by setting a value on passthroughLocale.passthroughLocaleName.

localizedData.pseudolocales = { }

This option allows pseudolocales to be generated from the strings in the default locale. This option takes an option with pseudolocales as keys and options for the pseudolocale package as values.

noStringsLocaleName = '...'

The value to replace the [locale] token with for chunks without localized strings. Defaults to "none"

runtimeLocaleExpression = '...'

A chunk of raw ECMAScript to inject into the webpack runtime to resolve the current locale at execution time. Allows multiple locales to share the same runtime chunk if it does not directly contain localized strings.

localizationStats = { }

localizationStats.dropPath = '...'

This option is used to designate a path at which a JSON file describing the localized assets produced should be written. If this property is omitted, the stats file won't be written.

The file has the following format:

{
  "entrypoints": {
    "<BUNDLE NAME>": {
      "localizedAssets": {
        "<LOCALE NAME>": "<ASSET NAME>",
        "<LOCALE NAME>": "<ASSET NAME>"
      }
    },
    "<BUNDLE NAME>": {
      "localizedAssets": {
        "<LOCALE NAME>": "<ASSET NAME>",
        "<LOCALE NAME>": "<ASSET NAME>"
      }
    }
  },
  "namedChunkGroups": {
    "<CHUNK NAME>": {
      "localizedAssets": {
        "<LOCALE NAME>": "<ASSET NAME>",
        "<LOCALE NAME>": "<ASSET NAME>"
      }
    },
    "<CHUNK NAME>": {
      "localizedAssets": {
        "<LOCALE NAME>": "<ASSET NAME>",
        "<LOCALE NAME>": "<ASSET NAME>"
      }
    }
  }
}

localizationStats.callback = (stats) => { ... }

This option is used to specify a callback to be called with the stats data that would be dropped at localizationStats.dropPath after compilation completes.

Links

@rushstack/webpack5-localization-plugin is part of the Rush Stack family of projects.