Namespace Pollution Mechanism
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0.3.1 • Public • Published


Converts gettext input (po/pot/mo files) into messageformat-compatible JSON, using gettext-parser.


npm install --save gettext-to-messageformat


yarn add gettext-to-messageformat

If using in an environment that does not natively support ES6 features such as object destructuring and arrow functions, you'll want to use a transpiler for this.


const { parsePo, parseMo } = require('gettext-to-messageformat')
const { headers, pluralFunction, translations } = parsePo(`
# Examples from
msgid ""
msgstr ""
"Content-Type: text/plain; charset=UTF-8\n"
"Language: pl\n"
"Plural-Forms: nplurals=3; plural=(n==1 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);\n"
msgid "Time: %1 second"
msgid_plural "Time: %1 seconds"
msgstr[0] "Czas: %1 sekunda"
msgstr[1] "Czas: %1 sekundy"
msgstr[2] "Czas: %1 sekund"
msgid "%1 took %2 ms to complete."
msgstr "Trebalo je %2 ms da se %1 završi."
msgid "%s took %d ms to complete."
msgstr "Trebalo je %2$d ms da se %1$s završi."
msgid "No star named %(starname)s found."
msgstr "Nema zvezde po imenu %(starname)s."
const MessageFormat = require('messageformat')
const mf = new MessageFormat({ [headers.language]: pluralFunction })
const messages = mf.compile(translations)
messages['Time: %1 second']([1])
// 'Czas: 1 sekunda'
messages['%s took %d ms to complete.'](['TASK', 42])
// 'Trebalo je 42 ms da se TASK završi.'
messages['No star named %(starname)s found.']({ starname: 'Chi Draconis' })
// 'Nema zvezde po imenu Chi Draconis.'

For more examples, gettext-parser includes a selection of .po and .mo files in its test fixtures.

API: parseMo(input, options) and parsePo(input, options)

The two functions differ only in their expectation of the input's format. input may be a string or a Buffer; options is an optional set of configuration for the parser, including the following fields:

  • defaultCharset (string, default null) – For Buffer input only, sets the default charset -- otherwise UTF-8 is assumed

  • forceContext (boolean, default false) – If any of the gettext messages define a msgctxt, that is used as a top-level key in the output, and all messages without a context are included under the '' empty string context. If no context is set, by default this top-level key is not included unless forceContext is set to true.

  • pluralFunction (function) – If your input file does not include a Plural-Forms header, or if for whatever reason you'd prefer to use your own, set this to be a stringifiable function that takes in a single variable, and returns the appropriate pluralisation category. Following the model used internally in messageformat, the function variable should also include cardinal as a member array of its possible categories, in the order corresponding to the gettext pluralisation categories. This is relevant if you'd like to avoid the new Function constructor otherwise used to generate pluralFunction, or to allow for more fine-tuned categories than gettext allows, e.g. differentiating between the categories of '1.0' and '1'.

  • verbose (boolean, default false) – If set to true, missing translations will cause warnings.

For more options, take a look at the source.

Both functions return an object containing the following fields:

  • headers (object) – The raw contents of the input file's headers, with keys lower-cased
  • pluralFunction (function) – An appropriate pluralisation function to use for the output translations, suitable to be used directly by messageformat. May be null if none was set in options and if the input did not include a Plural-Forms header.
  • translations (object) – An object containing the MessageFormat strings keyed by their msgid and if used, msgctxt.


npm i gettext-to-messageformat

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