THIS PACKAGE HAS BEEN DEPRECATED
Migration Guide
This package has deviated from the Intl.RelativeTimeFormat
spec rather heavily. Therefore, we've deprecated this package and add `@formatjs/intl-relativetimeformat as the spec-compliant polyfill.
- All
units
(such asday-short
) should be migrated similarly to:
new IntlRelativeFormat'en', .format Date.now - 1000;// will benew Intl.RelativeTimeFormat'en', .format-1, 'second'; new IntlRelativeFormat'en', .format Date.now - 48 * 3600 * 1000;// will benew Intl.RelativeTimeFormat'en', .format-2, 'day';
style: numeric
will becomenumeric: always
per spec (which is also the default)
new IntlRelativeFormat'en', .formatDate.now - 1000;// will benew Intl.RelativeTimeFormat'en', .format-1, 'second';
new IntlRelativeFormat'en', .format Date.now - 48 * 3600 * 1000;// will benew Intl.RelativeTimeFormat'en', .format-2, 'day';
style: 'best fit'
is a little trickier but we have released@formatjs/intl-utils
to ease the transition:
new IntlRelativeFormat'en', .formatDate.now - 1000;// will be;;new Intl.RelativeTimeFormat'en', .format diff.value, diff.unit;
new IntlRelativeFormat'en', .format Date.now - 48 * 3600 * 1000;// will be;;new Intl.RelativeTimeFormat'en', .format diff.value, diff.unit;
- If you were using
options.now
informat
, you can useformatjs/intl-utils
to transition as well
new IntlRelativeFormat'en', .formatDate.now - 1000, ;// will be;;new Intl.RelativeTimeFormat'en', .format diff.value, diff.unit;
new IntlRelativeFormat'en', .format Date.now - 48 * 3600 * 1000, ;// will be;;new Intl.RelativeTimeFormat'en', .format diff.value, diff.unit;
Intl RelativeFormat
Formats JavaScript dates to relative time strings (e.g., "3 hours ago").
Overview
Goals
This package aims to provide a way to format different variations of relative time. You can use this package in the browser and on the server via Node.js.
This implementation is very similar to moment.js, in concept, although it provides only formatting features based on the Unicode CLDR locale data, an industry standard that supports more than 200 languages.
How It Works
var rf = locales options;
The locales
can either be a single language tag, e.g., "en-US"
or an array of them from which the first match will be used. options
provides a way to control the output of the formatted relative time string.
var output = rf;
Common Usage Example
The most common way to use this library is to construct an IntlRelativeFormat
instance and reuse it many times for formatting different date values; e.g.:
var rf = 'en-US'; var posts = id: 1 title: 'Some Blog Post' date: 1426271670524 id: 2 title: 'Another Blog Post' date: 1426278870524 ; posts;// => "3 hours ago"// => "1 hour ago"
Features
-
Style options for
"best fit"
("yesterday") and"numeric"
("1 day ago") output based on thresholds. -
Units options for always rendering in a particular unit; e.g. "30 days ago", instead of "1 month ago".
-
Ability to specify the "now" value from which the relative time is calculated, allowing
format()
. -
Format output in relative time strings using `Intl.RelativeTimeFormat
-
Optimized for repeated calls to an
IntlRelativeFormat
instance'sformat()
method.
Usage
Intl
Dependency
This package assumes the following capabilities from Intl
:
If your environment does not support those, feel free to grab polyfills:
- https://www.npmjs.com/package/intl-pluralrules
- https://www.npmjs.com/package/@formatjs/intl-relativetimeformat
Loading IntlRelativeFormat in Node.js
Install package and polyfill:
npm install intl-relativeformat --save
Simply require()
this package:
var IntlRelativeFormat = ;var rf = 'en';var output = rf;
Bundling IntlRelativeFormat with Browserify/Webpack/Rollup
Install package:
npm install intl-relativeformat --save
Simply require()
this package and the specific locales you wish to support in the bundle:
var IntlRelativeFormat = ;
Note: in Node.js, the data for all 200+ languages is loaded along with the library, but when bundling it with Browserify/Webpack, the data is intentionally ignored (see package.json
for more details) to avoid blowing up the size of the bundle with data that you might not need.
Public API
IntlRelativeFormat
Constructor
To format a date to relative time, use the IntlRelativeFormat
constructor. The constructor takes two parameters:
-
locales - {String | String[]} - A string with a BCP 47 language tag, or an array of such strings. If you do not provide a locale, the default locale will be used. When an array of locales is provided, each item and its ancestor locales are checked and the first one with registered locale data is returned. See: Locale Resolution for more details.
-
[options] - {Object} - Optional object with user defined options for format styles. See: Custom Options for more details.
Note: The rf
instance should be enough for your entire application, unless you want to use custom options.
Locale Resolution
IntlRelativeFormat
uses a locale resolution process similar to that of the built-in Intl
APIs to determine which locale data to use based on the locales
value passed to the constructor. The result of this resolution process can be determined by call the resolvedOptions()
prototype method.
The following are the abstract steps IntlRelativeFormat
goes through to resolve the locale value:
-
If no extra locale data is loaded, the locale will always resolved to
"en"
. -
If locale data is missing for a leaf locale like
"fr-FR"
, but there is data for one of its ancestors,"fr"
in this case, then its ancestor will be used. -
If there's data for the specified locale, then that locale will be resolved; i.e.,
var rf = 'en-US';; // true -
The resolved locales are now normalized; e.g.,
"en-us"
will resolve to:"en-US"
.
Note: When an array is provided for locales
, the above steps happen for each item in that array until a match is found.
Custom Options
The optional second argument options
provides a way to customize how the relative time will be formatted.
Units
By default, the relative time is computed to the best fit unit, but you can explicitly call it to force units
to be displayed in "second"
, "second-short"
, "second-narrow"
, "minute"
, "minute-short"
, "minute-narrow"
, "hour"
, "hour-short"
, "hour-narrow"
, "day"
, "day-short"
, "day-narrow"
, "month"
, "month-short"
, "month-narrow"
, "year"
, "year-short"
or "year-narrow"
:
var rf = 'en' units: 'day';var output = rf;
As a result, the output will be "70 days ago" instead of "2 months ago".
Style
By default, the relative time is computed as "best fit"
, which means that instead of "1 day ago", it will display "yesterday", or "in 1 year" will be "next year", etc. But you can force to always use the "numeric" alternative:
var rf = 'en' style: 'numeric';var output = rf;
As a result, the output will be "1 day ago" instead of "yesterday".
resolvedOptions()
Method
This method returns an object with the options values that were resolved during instance creation. It currently only contains a locale
property; here's an example:
var rf = 'en-us';console; // => "en-US"
Notice how the specified locale was the all lower-case value: "en-us"
, but it was resolved and normalized to: "en-US"
.
format(date, [options])
Method
The format method (which takes a JavaScript date or timestamp) and optional options
arguments will compare the date
with "now" (or options.now
), and returns the formatted string; e.g., "3 hours ago" in the corresponding locale passed into the constructor.
var output = rf;console; // => "now"
If you wish to specify a "now" value, it can be provided via options.now
and will be used instead of querying Date.now()
to get the current "now" value.
License
This software is free to use under the Yahoo! Inc. BSD license. See the LICENSE file for license text and copyright information.