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Process string messages for translation from modules that use react-intl, specifically:

  • Parse and verify that messages are ICU-compliant w/o any syntax issues.
  • Remove description from message descriptor to save bytes since it isn't used at runtime.
  • Option to remove defaultMessage from message descriptor to save bytes since it isn't used at runtime.
  • Automatically inject message ID based on specific pattern.


npm i @formatjs/ts-transformer


The default message descriptors for the app's default language will be processed from: defineMessages(), defineMessage(), intl.formatMessage and <FormattedMessage>; all of which are named exports of the React Intl package.

Via ts-loader#

import {transform} from '@formatjs/ts-transformer'
module.exports = {  ...otherConfigs,  module: {    rules: [      {        test: /\.tsx?$/,        use: [          {            loader: 'ts-loader',            options: {              getCustomTransformers() {                return {                  before: [                    transform({                      overrideIdFn: '[sha512:contenthash:base64:6]',                    }),                  ],                }              },            },          },        ],      },    ],  },}

Via ts-jest in jest.config.js#


This requires ts-jest@26.4.0 or later

// jest.config.jsmodule.exports = {  // [...]  globals: {    'ts-jest': {      astTransformers: {        before: [          {            path: '@formatjs/ts-transformer/ts-jest-integration',            options: {              // options              overrideIdFn: '[sha512:contenthash:base64:6]',              ast: true,            },          },        ],      },    },  },}

Via ttypescript#

{  "compilerOptions": {    "plugins": [      {        "transform": "@formatjs/ts-transformer",        "import": "transform",        "type": "config",        "overrideIdFn": "[sha512:contenthash:base64:6]",        "ast": true      }    ]  }}

Via rollup-plugin-typescript2#

// rollup.config.jsimport typescript from 'rollup-plugin-typescript2'import {transform} from '@formatjs/ts-transformer'
export default {  input: './main.ts',
  plugins: [    typescript({      transformers: () => ({        before: [          transform({            overrideIdFn: '[sha512:contenthash:base64:6]',            ast: true,          }),        ],      }),    }),  ],}



A function with the signature (id: string, defaultMessage: string, description: string|object) => string which allows you to override the ID both in the extracted javascript and messages.

Alternatively, overrideIdFn can be a template string, which is used only if the message ID is empty.


Remove defaultMessage field in generated js after extraction.


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. Defaults to false.


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


Additional function names to extract messages from, e.g: ['$formatMessage']. Use this if you prefer to alias formatMessage to something shorter like $t.


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-projectimport {FormattedMessage} from 'react-intl';<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.


Pre-parse defaultMessage into AST for faster runtime perf. This flag doesn't do anything when removeDefaultMessage is true.

onMsgExtracted(filePath: string, msgs: MessageDescriptor[])#

Callback that gets triggered whenever a message is encountered.

onMetaExtracted(filePath: string, meta: Record<string, string>)#

Callback that gets triggered whenever a pragme meta is encountered.

Take a look at compile.ts for example in integration.