imf

This package is now deprecated in favor of intl-dom

A convenience wrapper for intl-messageformat.

Installation

npm install imf

Usage (Browser)

<script src="node_modules/intl-messageformat/dist/intl-messageformat-with-locales.min.js"></script>
<script src="node_modules/imf/dist/index.js"></script>

or:

import IMF from './node_modules/imf/dist/index-es6.js';

Usage (Node)

const IMF = require('imf');

Example

For the following JSON file structure...

{
    "Localized value!": "Chinese translation of \"Localized value!\"",
    "tablekey.Tablekey localized value!": "Chinese translation of \"tablekey.Tablekey localized value!\"",
    "tablekey": {
        "nestedMore": {
            "Tablekey localized value2": "Put another Chinese translation of \"tablekey.Tablekey localized value!\" here"
        }
    }
}

OR

{
    "Localized value!": "Chinese translation of \"Localized value!\"",
    "tablekey": {
        "Tablekey localized value!": "Chinese translation of \"tablekey.Tablekey localized value!\"",
        "nestedMore": {
            "Tablekey localized value2": "Put another Chinese translation of \"tablekey.Tablekey localized value!\" here"
        }
    }
}

OR

{
    "Localized value!": "Chinese translation of \"Localized value!\"",
    "tablekey.Tablekey localized value!": "Chinese translation of \"tablekey.Tablekey localized value!\"",
    "tablekey.nestedMore.Tablekey localized value2": "Put another Chinese translation of \"tablekey.Tablekey localized value!\" here"
}

...etc., one could do:

IMF({
    languages: ['zh-CN', 'en-US'],
    callback: function (l, getFormatter /*, enUSLocale, esLocale, ptLocale, zhCNLocale*/) {
        alert(l("Localized value!")); // Looks up "Localized value!" in Chinese file (at "locales/zh-CN.json") and in English (at "locales/en-US.json") if not present in Chinese
        const tk = getFormatter('tablekey');
        alert(tk("Tablekey localized value!")); // Equivalent to l("tablekey.Tablekey localized value!")

        // Note that the following two sets are equivalent
        const tk2 = getFormatter(['tablekey', 'nestedMore']);
        alert(tk2("Tablekey localized value2"));

        const tk3 = getFormatter('tablekey.nestedMore');
        alert(tk3("Tablekey localized value2"));
    }
});

API

Methods

• Constructor(options) - A constructor (which can be used without new) to be supplied an options object with the following optional properties:

  • languages - Array of BCP 47 language tags in order of preference. Can also be a string for a single tag (e.g., "en-US"), or, if not supplied, will default to navigator.language or en-US. Will be used as the second argument to the IntlMessageFormat constructor.

  • locales - Array of locale objects (see locale JSON file structure above). Will set the locales property if present. If present, langs should also be set.

  • langs - Array of BCP 47 language tags. Will be used to preset the langs property. Should only be provided if locales is manually provided.

  • fallbackLanguages - Allows a language or set of languages in the same format as languages. Its message will be supplied to the fallback callback argument of the formatter function (or used in a return value if fallback is not false) whenever no message is found for languages.

  • namespace - Initial namespace for the formatter function supplied as the first argument to callback. Defaults to value of defaultNamespace. Namespaces may be expressed as an array of namespace parts or as a string. Will be used in conjunction with a separator. See the example above for an illustration of the two allowable JSON file format structures. Note that namespace parts can be indefinitely nested whether as sub-objects or as additional separator-separated strings.

  • defaultNamespace - Used when a namespace is not provided to getFormatter. Defaults to empty string.

  • defaultSeparator - Separator to be used with namespaces. Defaults to ..

  • basePath - Base path for locale file resolution. Defaults to locales/.

  • localeFileResolver - Accepts a BCP 47 language tag as an argument, and should return a file path for obtaining the corresponding JSON locale file. Defaults to a function which uses basePath and then adds .json to the supplied language tags for the file name within the base path.

  • callback - Invoked upon the IMF() object and supplied with the following arguments upon loading of locales:

    1. A formatter function based on namespace (or defaultNamespace or the empty string if none supplied)

    2. A generic formatter building function (see getFormatter method)

    3. Retrieved locale files as JSON objects; to get all locale files, use this.locales from within your callback.

    4. Retrieved fallback locale files as JSON objects; to get all fallback locale files, use this.fallbackLocales from within your callback.

• getFormatter(ns, sep) - A generic formatter building method; can be supplied an optional namespace and optional separator, defaulting otherwise to defaultNamespace and defaultSeparator, respectively. The namespace can either be an array of namespace parts or a string with the separator already applied. The namespace (along with separator interpolated between and after) will be prepended to the key supplied by the user when the formatter function is called. Will be automatically invoked (and the result supplied to callback) if callback or languages is supplied upon instantiation. The returned formatter function can be called with the following arguments (supplied in order or with a single object with properties of the given name):

  1. key - Lookup key for a IntlMessageFormat-formatted message in the locales file (will be prepended as per the above by any supplied namespaces and separators). If no values or formats objects are supplied, the literal value from the locales file will be returned without any IntlMessageFormat processing. If supplied as an array, the last item will be treated as the key whereas the prior portions will be treated as a namespace override. Likewise if a separator-separated string is supplied.

  2. values - Optional values object (same as accepted by IntlMessageFormat.format())

  3. formats - Optional formats object (same as accepted by third argument to the IntlMessageFormat constructor).

  4. fallback - Optional fallback function or boolean. If a function, fallback will be called whenever a message cannot be found, and will be supplied a single object argument with properties, message, langs, namespace, separator, key, values, and formats and whose return value will be used for the return value of the formatter function. Might be used to return a different structure to indicate a need for different directionality (e.g., if an Arabic message is not found, the fallback can be used to return a value which can be used to indicate the English one can be displayed left to right). If an otherwise non-false value is supplied for fallback (or the argument is omitted), any message for fallbackLocales (if any) will be returned instead. If no message has been found and no fallbacks provided, an error will be thrown.

• loadLocales(langs, cb, avoidSettingLocales) - Loads the locale file objects. Will be automatically invoked if callback or languages is supplied upon instantiation. The second callback argument is optional and will be invoked with each locale object as an argument after the locales have loaded (with the locales also available as an array of objects on the locales property (and used by formatters) unless avoidSettingLocales is supplied).

Properties

• langs - Will automatically be set (as an array of BCP 47 language tags) upon calls to loadLocales or if the langs option is supplied upon instantiation. Utilized in error messages when no message or fallback message can be found.

• locales - Will automatically be set to an (empty) array. If loadLocales is run (including by the use of languages or callback options arguments to the constructor), the retrieved locale JSON objects will be added to this array. This property can also be set as an array of (pre-loaded) locales at instantiation. If supplied after instantiation, these will replace any already set.

• fallbackLocales - Will automatically be set to an array. Defaults to an empty array. If fallbackLanguages is provided, the locale JSON objects loaded by loadLocales will be added to this array. This property can also be set as an array of (pre-loaded) locales at instantiation. If supplied after instantiation, these will replace any already set. Unless the fallback argument provided to getFormatter is set to false, these fallback locales will be checked whenever getFormatter does not find a message within the locales property.

• fallbackLanguages Will automatically be set.

To-dos

1. Add utility for auto-setting document.title, html.lang, and html.dir
2. Some code like this to import Yahoo's locale files (plural rules and sublanguages) (or if necessary calling IntlMessageFormat.__addLocaleData() ourselves). Won't be necessary for browser in future if implemented

const text = (await fetch('path/to/Yahoo/IntlMessageFormat/dist/locale-data/XX.js')).text();
console.log(text);

1. Support JSONP (allowing for multi-line template strings or other deviants from non-JSON syntax like single quotes).
2. Add logic to recover if file like en-US.json is not present but en.json is (might enhance getJSON errBack to capture thrown object with file property indicating the file causing the error).