Installation#

npm i -D @formatjs/cli

Add the following command to your package.json scripts:

{
  "scripts": {
    "extract": "formatjs extract",
    "compile": "formatjs compile"
  }
}

Native CLI (Rust)#

Installation#

Download pre-built binaries for your platform:

# Download and install
curl -L https://github.com/formatjs/formatjs/releases/download/formatjs_cli_v0.1.6/formatjs-darwin-arm64 -o formatjs
chmod +x formatjs
sudo mv formatjs /usr/local/bin/

# Verify
formatjs --version

Benefits#

• 🚀 4-17x Faster: Dramatically faster extraction and compilation
• 📦 Zero Dependencies: Single binary, no Node.js or npm required
• 💾 Low Memory: Minimal memory footprint
• ⚡ Instant Startup: No Node.js initialization overhead
• 🔧 CI/CD Friendly: Perfect for build pipelines and automation

Usage#

The native CLI is a drop-in replacement with identical command-line interface:

# Extract messages
formatjs extract "src/**/*.{ts,tsx}" --out-file messages.json

# Compile translations
formatjs compile "lang/*.json" --out-file compiled.json --ast

# Verify translations
formatjs verify "lang/*.json" --source-locale en --missing-keys

All the same options and formatters work with the native CLI. See the sections below for detailed documentation.

We've built this CLI that helps you extract messages from a list of files. It uses @formatjs/ts-transformer under the hood and should be able to extract messages if you're declaring using 1 of the mechanisms below:

defineMessages({
  foo: {
    id: 'foo',
    defaultMessage: 'foo',
    description: 'bar',
  },
})

defineMessage({
  id: 'single',
  defaultMessage: 'single message',
  description: 'header',
})

<FormattedMessage id="foo" defaultMessage="foo" description="bar" />

function Comp(props) {
  const {intl} = props
  return intl.formatMessage({
    // The whole `intl.formatMessage` is required so we can extract
    id: 'foo',
    defaultMessage: 'foo',
    description: 'bar',
  })
}

Extraction#

npm run extract -- --help
# Usage: formatjs extract [options] [files...]

# Extract string messages from React components that use react-intl.
# The input language is expected to be TypeScript or ES2017 with JSX.

npm run extract -- "src/**/*.{ts,tsx,vue}" --out-file lang.json

--format [path]#

Path to a formatter file that controls the shape of JSON file from --out-file. The formatter file must export a function called format with the signature.

type FormatFn = <T = Record<string, MessageDescriptor>>(
  msgs: Record<string, MessageDescriptor>
) => T

This is especially useful to convert from our extracted format to a TMS-specific format.

See our builtin formatters for examples.

--in-file [path]#

The file containing list of file paths to extract. This is useful to bypass bash command line limit.

--out-file [path]#

The target file path where the plugin will output an aggregated .json file of allthe translations from the files supplied. This flag will ignore --messages-dir

--id-interpolation-pattern [pattern]#

If certain message descriptors don't have id, this pattern will be used to automatically generate IDs for them. Default to [sha512:contenthash:base64:6]. See nodejs crypto createHash for hash algorithms & nodejs buffer docs for digest encodings.

--extract-source-location#

Whether the metadata about the location of the message in the source file should be extracted. If true, then file, start, and end fields will exist for each extracted message descriptors. (default: false)

--additional-component-names [comma-separated-names]#

Additional component names to extract messages from, e.g: ['FormattedFooBarMessage']. NOTE: By default we check for the fact that FormattedMessage is imported from moduleSourceName to make sure variable alias works. This option does not do that so it's less safe.

--additional-function-names [comma-separated-names]#

Additional function names to extract messages from, e.g: ['$formatMessage'].

--ignore [files]#

List of glob paths to not extract translations from.

--throws#

Whether to throw an exception when we fail to process any file in the batch.

--pragma [pragma]#

Parse specific additional custom pragma. This allows you to tag certain file with metadata such as project. For example with this file:

// @intl-meta project:my-custom-project
<FormattedMessage defaultMessage="foo" id="bar" />

and with option {pragma: "intl-meta"}, we'll parse out // @intl-meta project:my-custom-project into {project: 'my-custom-project'} in the result file.

--preserve-whitespace#

Whether to preserve whitespace and newlines in output. We typically remove consecutive whitespaces and newlines since those often gets abused for styling purposes.

--flatten#

Whether to hoist selectors & flatten sentences as much as possible. E.g:

I have {count, plural, one{a dog} other{many dogs}}

becomes

{count, plural, one{I have a dog} other{I have many dogs}}

The goal is to provide as many full sentences as possible since fragmented sentences are not translator-friendly.

Verification#

Verify translation files to make sure keys are translated and messages are structurally compatible with source locale.

npm run formatjs verify [options] <translationFiles>

--source-locale <sourceLocale>#

The source locale of the translation files. There must be a file named <sourceLocale>.json in the list of translation files. This is used as source to verify other translations against.

--missing-keys#

Whether to check for missing keys in target locale compared to source locale. This basically guarantees that no messages are untranslated.

--structural-equality#

Whether to check for structural equality of messages between source and target locale. This makes sure translations are formattable and are not missing any tokens.

--extra-keys#

Whether to check for keys that exist in the target locale but not in the source locale. This ensures that translation files do not contain obsolete or unused keys.

Compilation#

Compile extracted files from formatjs extract to a react-intl consumable JSON file. This also does ICU message verification. See Message Distribution for more details.

npm run compile -- --help

--format [path]#

Path to a formatter file that converts <translation_file> to Record<string, string> so we can compile. The file must export a function named compile with the signature:

type CompileFn = <T = Record<string, MessageDescriptor>>(
  msgs: T
) => Record<string, string>

This is especially useful to convert from a TMS-specific format back to react-intl format.

See our builtin formatters for examples.

--out-file <output>#

The target file that contains compiled messages.

--ast#

Whether to compile message into AST instead of just string. See Advanced Usage

--pseudo-locale <pseudoLocale>#

Whether we should compile messages into pseudo locales instead. Available pseudo-locales:

Given the English message my name is {name}

Extraction and compilation with a single script#

In some environments you may want to simply extract your messages to a file ready for use with react-intl without using an intermediary extracted message file format. This could be useful for quickly and easily creating the file for the original language that uses the default messages. This could also be useful if you use a Translation Management System (TMS) that is best suited to working with the compiled files. Keep in mind that the compiled file does not contain message descriptions so it is harder to work with for translators. Ideally you want to find or write a custom formatter you can use to extract messages into a file format that works with your TMS.

In order to achieve extraction and compilation in a single script, you can simply set up a script for that in package.json like in this example:

"scripts": {
  "extract": "formatjs extract",
  "compile": "formatjs compile",
  "extract-compile": "formatjs extract 'src/**/*.ts*' --out-file temp.json --flatten --id-interpolation-pattern '[sha512:contenthash:base64:6]' && formatjs compile 'temp.json' --out-file lang/en.json && rm temp.json"
}

Breakdown of the script#

The extract-compile example script consists of three operations performed one after the other.

formatjs extract 'src/**/*.ts*' --out-file temp.json --flatten --id-interpolation-pattern '[sha512:contenthash:base64:6]'

The first script extracts messages from all typescript files that are located in subfolders of src. You may need to ignore certain files that could trigger errors or warnings in the script, such as --ignore myFolder/myFile.ts

formatjs compile 'temp.json' --out-file lang/en.json

The second script compiles the messages from temp.json into the file lang/en.json. This file is ready to be consumed by react-intl.

rm temp.json

The last script deletes the temp.json extracted file. Feel free remove this from the script if you wish to keep this file around.

The resulting files#

Here you can see the difference between the extracted (using the default formatter) and the compiled file formats. In the script above, temp.json is the extracted file and en.json is the compiled file.

{
  "hak27d": {
    "defaultMessage": "Control Panel",
    "description": "title of control panel section"
  },
  "haqsd": {
    "defaultMessage": "Delete user {name}",
    "description": "delete button"
  },
  "19hjs": {
    "defaultMessage": "New Password",
    "description": "placeholder text"
  },
  "explicit-id": {
    "defaultMessage": "Confirm Password",
    "description": "placeholder text"
  }
}

Folder Compilation#

Batch compile a folder with extracted files from formatjs extract to a folder containing react-intl consumable JSON files. This also does ICU message verification. See Message Distribution for more details.

npm run formatjs compile-folder [options] <folder> <outFolder>

Folder structure should be in the form of <folder>/<locale>.json and the output would be <outFolder>/<locale>.json.

--format [path]#

Path to a formatter file that converts <translation_file> to Record<string, string> so we can compile. The file must export a function named compile with the signature:

type CompileFn = <T = Record<string, MessageDescriptor>>(
  msgs: T
) => Record<string, string>

This is especially useful to convert from a TMS-specific format back to react-intl format

--ast#

Whether to compile message into AST instead of just string. See Advanced Usage

--skip-errors#

Whether to continue compiling messages after encountering an error parsing one of them. Any keys with errors will not be included in the output file.

Builtin Formatters#

We provide the following built-in formatters to integrate with 3rd party TMSes:

Custom Formatters#

You can provide your own formatter by using our interfaces:

interface VendorJson {}

// [Optional] Format @formatjs/cli structure to vendor's structure
export const format: FormatFn<VendorJson> = () => {}
// [Optional] Format vendor's structure to @formatjs/cli structure
export const compile: CompileFn<VendorJson> = () => {}
// [Optional] Sort the messages in a specific order during serialization
export const compareMessages: Comparator = () => {}

Take a look at our builtin formatter code for some examples.

Node API#

Install @formatjs/cli-lib instead to use programmatically

npm i -D @formatjs/cli-lib

Extraction#

const resultAsString: Promise<string> = extract(files, {
  idInterpolationPattern: '[sha512:contenthash:base64:6]',
})

Compilation#

const resultAsString: Promise<string> = compile(files, {
  ast: true,
})

Custom Formatter#

export const format: FormatFn = msgs => msgs

// Sort key reverse alphabetically
export const compareMessages = (el1, el2) => {
  return el1.key < el2.key ? 1 : -1
}

export const compile: CompileFn = msgs => {
  const results: Record<string, string> = {}
  for (const k in msgs) {
    results[k] = msgs[k].defaultMessage!
  }
  return results
}