Our i18n library relies on the wonderful iLib library. It provides many useful tools for things like string translation, date/time formatting, number parsing, etc.

You must install iLib as a dependency in your application to use the i18n module:

npm install ilib@^14.2.0

We will cover a good deal of how to use iLib inside your Enact app below, but we will not cover everything.

If you wish to learn more about ilib checkout their github and docs.

Accessing iLib from Enact

You can use iLib like this:

import DateFmt from 'ilib/lib/DateFmt';

const formatter = new DateFmt({
	date: 'dmwy',
	length: 'full',
	timezone: 'local',
	useNative: false

Translating Strings


ilib/ResBundle, the resource bundle class, represents a set of translated strings. Each app has its own resource bundle. These bundles are loaded dynamically, with each one having a name and locale.

The locale may be specified as an option in the constructor.

	import ResBundle from 'ilib/lib/ResBundle';
	const rb = new ResBundle({locale: "ko-KR"});

In practical terms, ResBundle’s most important method is getString().

	const str = toIString("My Label");

The actual data contained in the bundle is stored under the application’s resources directory. Within resources is a hierarchy of subdirectories named for locales. iLib reads translated strings from strings.json files found in these directories.

In the layered structure of the locale directories, values from deeper levels override those from nearer the surface, as in the following example:

		strings.json - shared strings for all English
		appinfo.json - application description
			strings.json - only strings special to Canada
			strings.json - only strings special to Great Britain

For the en-GB locale, if a string value is defined in both /resources/en/strings.json and /resources/en/GB/strings.json, the value from the latter (more-specific) file will override the value from the former file.

It’s worth noting that, in addition to strings, other localized files (such as appinfo.json) may also be placed in these hierarchical directories, with their data following the same rules of precedence. In the case of appinfo.json, the locale-specific files will typically include values for “title”, “keywords”, and “description”. The other properties will keep the values inherited from the app’s top-level appinfo.json.

$L() is a convience method for ResBundle, it is described in the main section of the i18n docs here

Using iLib for formatting

String Formatting

ilib/IString is used to format strings. You will not generally need to require IString directly to use it. Its format() method allows for interpolation of named parameters into the string. The following syntax is recommended:

	import {toIString} from 'i18n/$L'

	const template = toIString("There are {n} objects.");
	const str = template.format({n: 15});

str now has the value "There are 15 objects."

Note that we are populating template by calling toIString() on the localized resource bundle $L.rb. This is because format() accepts an ilib/IString object, but not an intrinsic JavaScript string. (A call to toIString() on a resource bundle returns an instance of ilib/IString, while a call to $L() returns an intrinsic JavaScript string.)

ilib/IString has the same methods as an intrinsic string, and in many cases may be used as a substitute. For those places that require an intrinsic string, you must call the toString() method to convert the ilib/IString to an intrinsic string.

Handling Plurals

ilib/IString uses the formatChoice() method to handle plurals. This allows translators to adjust strings to handle plurals properly for their respective languages.

	const number = 3;
	const template = toIString( "0#There are no objects.|1#There is 1 object.|#There are {n} objects.");
	const str = template.formatChoice(number, {n: number});

str now has the value "There are 3 objects."

formatChoice() also supports number classes (“zero”, “one”, “two”, “few” and “many”) for languages with complex rules for pluralization, such as Russian or Serbian.

	const template = toIString( "0#There are no objects.|few#There are a few ({n}) objects.|#There are many objects. ({n})");

Dates and Times

The formatting of dates and times can differ widely from one locale to the next:

 Locale    Format
--------- --------------------------
 en-US     Mo 11/12/2012 2:30pm

 en-CA     Mo 12/11/2012 2:30 PM

 de-DE     14:30 Mo 12.11.2012

 zh-CN     2012-11-12周一下午2:30

 it-IT     Lu 12/11/2012 14.30

In iLib, the ilib/DateFmt class is used to format dates and times. The constructor accepts various options, which control how the formatter behaves. Once you create a DateFmt instance, you may call its format() method as many times as you want to format dates according to the given set of options.

	import DateFmt from 'ilib/lib/DateFmt';
	const fmt = new DateFmt();
	const d = fmt.format(date);

Among the options you may specify are the following:

  • Which locale to use
  • Whether to format the date only, time only, or both date and time together
  • Which components of the date or time to format (e.g., only format the month and year components of the date)
  • Whether to use a 12-hour clock, a 24-hour clock, or the default clock for the locale
  • Whether to use short, medium, long, or full-length text for components that use words (e.g., Sunday may be expressed as “S”, “Su”, “Sun”, or “Sunday”)
  • Which time zone to format for
	const fmt = new DateFmt({ locale: "tr-TR",
		type: "date", date: "dmy", timezone: "Europe/Istanbul"

Calendar Dates

iLib also supports the formatting of dates in multiple calendaring systems, with the default being the familiar Gregorian calendar.

To create a date, you may call the factory method or use the calendar date directly, e.g.:

	import HebrewDate from 'ilib/lib/HebrewDate';
	const now = new HebrewDate();

This is equivalent to the following factory method call:

	import dateFactory from 'ilib/lib/DateFactory';
	const now = dateFactory({type: "hebrew"});

Dates may be converted between calendars via a “Julian Day” number. A Julian Day is the number of whole days and fractions of a day since the beginning of the epoch on 24 November -4713 BCE (Gregorian):

	const now = dateFactory();
	// now.year is currently 2013
	const jd = now.getJulianDay();
	const hebrewDate = new HebrewDate({julianday: jd});
	// hebrewDate.year is 5773

To format a date in a non-Gregorian Calendar, follow the pattern of creating a DateFmt object and calling format() on it.

	const fmt = new DateFmt({
		length: "full",
		locale: "en-US",
		calendar: "hebrew"
	const d = fmt.format(date);

The value of d is "Adar 27, 5773 11:47PM PDT".

Use ilib/CalendarFactory as a factory method to create the other calendar types.

	import calendarFactory from 'ilib/lib/CalendarFactory';
	const cal = calendarFactory({
		// looks up calendar for this locale
		locale: "nl-NL"
	const days = cal.getMonLength(2, year);

days is 28 in regular years and 29 in leap years.

Ranges and Durations

ilib/DateRngFmt may be used to format a date/time range—a period of time with a specific start point and end point. As with the other formatter classes, the final output (e.g., 'Mar 11-14, 2013') will depend on the options supplied to the formatter.

Similarly, ilib/DurationFmt lets you format durations—how long things take to happen. Again, you may customize the output (e.g., '36 hours, 24 minutes, and 37 seconds') by setting the formatter’s options.

Time Zones

In many countries, the national government determines the time zone. In some countries, including the United States, this may be overridden by smaller jurisdictions such as states/provinces, counties, towns, etc. Time zones are specified using the IANA convention of “continent/city” (e.g., 'America/Los_Angeles' or 'Asia/Seoul').

ilib/TimeZone represents information about a particular time zone. Instances may be passed to other classes such as ilib/DateFmt, although the specifier string itself is also accepted.

	import TimeZone from 'ilib/lib/TimeZone';
	const tz = new TimeZone({
		id: "America/Los_Angeles"
	const offset = tz.getOffset(dateFactory());

offset is now {h: -8, m: 0}.

Numeric Values

The formatting of numeric values—in numbers, currency, and percentages—is another locale-sensitive process.

 Locale    Float           Currency       Percentage
--------- --------------- -------------- ---------------
 en-US     1,234,567.89    $1,234.56      57.2%

 de-DE     1.234.567,89    1.234,56 €     57,2 %

 fr-FR     1 234 567,89    1 234,56 €     57,2%

 tr-TR     1.234.567,89    1.234,56 TL    % 57,2

As shown in the following examples, iLib handles each of these cases using ilib/NumFmt.


	import NumFmt from 'ilib/lib/NumFmt';
	const fmt = new NumFmt({
		locale: "de-DE"
	const str = fmt.format(1234567.89);

str is now '1.234.567,89'.


	const fmt = new NumFmt({
		style: "currency",
		currency: "EUR",
		locale: "de-DE"
	const amount = fmt.format(1234.56289);

amount is now '1.234,56 €'.


	const fmt = new NumFmt({
		style: "percentage",
		maxFractionDigits: 2,
		locale: "tr-TR"
	const percentString = fmt.format(0.893453);

percentString is now '% 89,34'.