javascript-time-ago

What is javascript-time-ago?

The `javascript-time-ago` npm package is used to format dates and times in a human-readable way, such as '5 minutes ago' or '2 days ago'. It supports multiple languages and locales, making it a versatile tool for internationalization.

What are javascript-time-ago's main functionalities?

Basic Usage

This feature allows you to format a date into a human-readable string indicating the time elapsed since that date. The example shows how to set up the package for English and format a date to '1 minute ago'.

const TimeAgo = require('javascript-time-ago');
const en = require('javascript-time-ago/locale/en');
TimeAgo.addLocale(en);
const timeAgo = new TimeAgo('en-US');
console.log(timeAgo.format(new Date(Date.now() - 60 * 1000))); // '1 minute ago'

Custom Styles

This feature allows you to define custom styles for formatting the elapsed time. The example demonstrates how to create a custom style and use it to format a date.

const TimeAgo = require('javascript-time-ago');
const en = require('javascript-time-ago/locale/en');
TimeAgo.addLocale(en);
const timeAgo = new TimeAgo('en-US');
const customStyle = {
  steps: [
    { formatAs: 'second' },
    { formatAs: 'minute' },
    { formatAs: 'hour' },
    { formatAs: 'day' },
    { formatAs: 'week' },
    { formatAs: 'month' },
    { formatAs: 'year' }
  ]
};
console.log(timeAgo.format(new Date(Date.now() - 60 * 1000), customStyle)); // '1 minute ago'

Localization

This feature supports multiple languages and locales, allowing you to format dates in different languages. The example shows how to set up the package for both English and Spanish.

const TimeAgo = require('javascript-time-ago');
const en = require('javascript-time-ago/locale/en');
const es = require('javascript-time-ago/locale/es');
TimeAgo.addLocale(en);
TimeAgo.addLocale(es);
const timeAgoEn = new TimeAgo('en-US');
const timeAgoEs = new TimeAgo('es-ES');
console.log(timeAgoEn.format(new Date(Date.now() - 60 * 1000))); // '1 minute ago'
console.log(timeAgoEs.format(new Date(Date.now() - 60 * 1000))); // 'hace 1 minuto'

Other packages similar to javascript-time-ago

moment

Moment.js is a widely-used library for parsing, validating, manipulating, and formatting dates. It offers extensive functionality for date and time manipulation, but it is larger in size compared to `javascript-time-ago` and has been deprecated in favor of more modern solutions.

date-fns

date-fns provides a comprehensive set of functions for working with dates in JavaScript. It is modular, allowing you to import only the functions you need, which can result in smaller bundle sizes. It also supports internationalization, similar to `javascript-time-ago`.

timeago.js

timeago.js is a small library used to format dates in a 'time ago' style. It is lightweight and easy to use, but it may not offer as many customization options or support for as many locales as `javascript-time-ago`.

README

javascript-time-ago

International higly customizable relative date/time formatter (both for past and future dates).

Formats a date/timestamp to:

• just now
• 5m
• 15 min
• 25 minutes
• an hour ago
• 1 mo.
• 5 years ago
• … or whatever else

For React users there's also a React component.

Usage

npm install javascript-time-ago --save

import TimeAgo from 'javascript-time-ago'

// Load locale-specific relative date/time formatting rules.
import en from 'javascript-time-ago/locale/en'

// Add locale-specific relative date/time formatting rules.
TimeAgo.locale(en)

// Create relative date/time formatter.
const timeAgo = new TimeAgo('en-US')

timeAgo.format(new Date())
// "just now"

timeAgo.format(Date.now() - 60 * 1000)
// "a minute ago"

timeAgo.format(Date.now() - 2 * 60 * 60 * 1000)
// "2 hours ago"

timeAgo.format(Date.now() - 24 * 60 * 60 * 1000)
// "a day ago"

Russian

import TimeAgo from 'javascript-time-ago'

// Load locale-specific relative date/time formatting rules.
import en from 'javascript-time-ago/locale/en'
import ru from 'javascript-time-ago/locale/ru'

// Add locale-specific relative date/time formatting rules.
TimeAgo.locale(en)
TimeAgo.locale(ru)

// cyka blyat
const timeAgo = new TimeAgo('ru-RU')

timeAgo.format(new Date())
// "только что"

timeAgo.format(Date.now() - 60 * 1000)
// "минуту назад"

timeAgo.format(Date.now() - 2 * 60 * 60 * 1000)
// "2 часа назад"

timeAgo.format(Date.now() - 24 * 60 * 60 * 1000)
// "днём ранее"

Twitter style

Mimics Twitter style of time ago ("1m", "2h", "Mar 3", "Apr 4, 2012")

timeAgo.format(new Date(), 'twitter')
// ""

timeAgo.format(Date.now() - 60 * 1000, 'twitter')
// "1m"

timeAgo.format(Date.now() - 2 * 60 * 60 * 1000, 'twitter')
// "2h"

timeAgo.format(Date.now() - 2 * 24 * 60 * 60 * 1000, 'twitter')
// "Mar 3"

timeAgo.format(Date.now() - 365 * 24 * 60 * 60 * 1000, 'twitter')
// "Mar 5, 2017"

Twitter style uses Intl for formatting day/month/year labels. If Intl is not available then it falls back to the default style.

"Just time" style

timeAgo.format(Date.now() - 60 * 1000, 'time')
// "1 minute"

Similar to the default style but with "ago" omitted:

• just now
• 1 minute
• 2 minutes
• 5 minutes
• 10 minutes
• 15 minutes
• 20 minutes
• half an hour
• 1 hour
• 2 hours
• …
• 20 hours
• 1 day
• 2 days
• 3 days
• 4 days
• 5 days
• 1 week
• 2 weeks
• 3 weeks
• 1 month
• 2 months
• 3 months
• 4 months
• half a year
• 1 year
• 2 years
• 3 years
• …

Loading locales

No locale data is loaded by default: a developer must manually choose which locales must be loaded. This is to reduce the resulting javascript bundle size.

If the resulting bundle size is of no concern (e.g. a big enterprise application), or if the code is being run on server side (e.g. Server-Side Rendering), then use this helper to load all available locales:

require('javascript-time-ago/load-all-locales')

RelativeTimeFormat

There's a spec proposal called Intl.RelativeTimeFormat suggesting web browsers implement "time ago" formatting natively like they already do for dates and numbers. It's still a draft, and not officially accepted yet, but I guess at some point in time it will be accepted, in which case this library could serve as a polyfill for older browsers (iOS, Android).

import JavascriptTimeAgo, { RelativeTimeFormat } from 'javascript-time-ago'
import en from 'javascript-time-ago/locale/en'

JavascriptTimeAgo.locale(en)
// Returns "2 days ago"
new RelativeTimeFormat('en').format(-2, 'day')

Advanced

The above sections explained all the basics required for using this library in a project.

This part of the documentation contains some advanced topics for those willing to have a better understanding of how this library works internally.

Customization

Localization can be further customized by selecting one of the "flavours": long, short, or mabe some others (like tiny defined for en). Refer to locale/en for an example.

import english from 'javascript-time-ago/locale/en'

english.tiny  // '1s', '2m', '3h', '4d', …
english.short // '1 sec. ago', '2 min. ago', …
english.long  // '1 second ago', '2 minutes ago', …

One can pass style (string or object) as a second parameter to the .format(date, style) function. The style object can specify (all are optional):

• flavour – preferred labels variant (e.g. short, long)
• units – a list of time interval measurement units which can be used in the formatted output (e.g. ['second', 'minute', 'hour'])
• gradation – custom time interval measurement units scale
• custom – a function of { elapsed, time, date, now, locale }. If this function returns a value, then the .format() call will return that value. Otherwise the date/time is formatted as usual.

(see twitter style for an example)

Gradation

A gradation is a list of time interval measurement steps.

[
  {
    unit: 'second',
  },
  {
    unit: 'minute',
    factor: 60,
    threshold: 59.5
  },
  {
    unit: 'hour',
    factor: 60 * 60,
    threshold: 59.5 * 60
  },
  …
]

Each step is described by:

• unit — a localized time measurement unit: second, minute, hour, day, month, year are the standardized CLDR ones.
• factor — a divider for the supplied time interval (in seconds).
• threshold — a minimum time interval value (in seconds) required for this gradation step. Each step must have a threshold defined except for the first one. Can a number or a function(now) returning a number. Some advanced threshold customization is possible like threshold_for_[prev-unit] (see ./source/gradation/convenient.js).
• granularity — for example, 5 for minute to allow only 5-minute intervals: 0 minutes, 5 minutes, 10 minutes, etc.

If a gradation step should output not simply a time interval of a certain time unit but something different instead then it may be described by:

• unit — a localized time measurement unit: second, minute, hour, day, month, year are the standardized CLDR ones.
• factor — a divider for the supplied time interval (in seconds).
• threshold — a minimum time interval value (in seconds) required for this gradation step. Each step must have a threshold defined except for the first one. Can a number or a function(now) returning a number. Some advanced threshold customization is possible like threshold_for_[prev-unit] (see ./source/gradation/convenient.js).
• granularity — for example, 5 for minute to allow only 5-minute intervals: 0 minutes, 5 minutes, 10 minutes, etc.

For more gradation examples see source/gradation folder.

• threshold — same as above.
• format — a function(value, locale) returning a string. value argument is the date/time being formatted as passed to TimeAgo.format(value): either a number or a Date. locale argument is the selected locale (aka "BCP 47 language tag", e.g. ru-RU). For example, the built-in Twitter gradation has regular minute and hour steps followed by a custom one formatting a date as "day/month/year", e.g. Jan 24, 2018.

Built-in gradations:

import {
  canonical, // '1 second ago', '2 minutes ago', …
  convenient // 'just now', '5 minutes ago', …
} from 'javascript-time-ago/gradation'

Localization internals

The localization resides in the locale folder.

The format a localization is:

{
  …
  "day":
  {
    "past":
    {
      "one": "{0} day ago",
      "other": "{0} days ago"
    },
    "future":
    {
      "one": "in {0} day",
      "other": "in {0} days"
    }
  },
  …
}

The past and future can be defined by any of: zero, one, two, few, many and other. For more info on which is which read the official Unicode CLDR documentation. Unicode CLDR (Common Locale Data Repository) is an industry standard and is basically a collection of formatting rules for all locales (date, time, currency, measurement units, numbers, etc).

To determine whether a certain amount of time (number) is one, few, or something else, javascript-time-ago uses Unicode CLDR rules for formatting plurals. These rules are number quantifying functions (one for each locale) which can tell if a number should be treated as zero, one, two, few, many or other. Knowing how these pluralization rules work is not required but anyway here are some links for curious advanced readers: rules explanation, list of rules for all locales, converting those rules to javascript functions. These quantifying functions can be found as quantify properties of a locale data.

Future

When given future dates .format() produces the corresponding output, e.g. "in 5 minutes", "in a year", etc.

Default

The default locale is en and can be changed: TimeAgo.defaultLocale = 'ru'.

React

There is also a React component built upon this library which autorefreshes itself.

Intl

Intl global object is not required for this library, but it may be required if you choose to use the built-in twitter style (though it will fall back to the default style if Intl is not available).

Intl is present in all modern web browsers and is absent from some of the old ones: Internet Explorer 10, Safari 9 and iOS Safari 9.x (which can be solved using Intl polyfill).

Node.js starting from 0.12 has Intl built-in, but only includes English locale data by default. If your app needs to support more locales than English on server side (e.g. Server-Side Rendering) then you'll need to use Intl polyfill.

Applying Intl polyfill:

npm install intl@1.2.4 --save

Node.js

import IntlPolyfill from 'intl'

const locales = ['en', 'ru', ...]

if (typeof Intl === 'object') {
  if (!Intl.DateTimeFormat || Intl.DateTimeFormat.supportedLocalesOf(locales).length !== locales.length) {
    Intl.DateTimeFormat = IntlPolyfill.DateTimeFormat
  }
}
else {
  global.Intl = IntlPolyfill
}

Web browser: only download intl package if the web browser doesn't support it, and only download the required locale.

async function initIntl() {
  if (typeof Intl === 'object') {
    return
  }
  await Promise.all([
    import('intl'),
    import('intl/locale-data/jsonp/en'),
    import('intl/locale-data/jsonp/ru'),
    ...
  ])
}

initIntl().then(...)

Contributing

After cloning this repo, ensure dependencies are installed by running:

npm install

This module is written in ES6 and uses Babel for ES5 transpilation. Widely consumable JavaScript can be produced by running:

npm run build

Once npm run build has run, you may import or require() directly from node.

After developing, the full test suite can be evaluated by running:

npm test

When you're ready to test your new functionality on a real project, you can run

npm pack

It will build, test and then create a .tgz archive which you can then install in your project folder

npm install [module name with version].tar.gz

License

MIT