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javascript-time-ago
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2.5.11 • Public • Published

javascript-time-ago

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Localized relative date/time formatting (both for past and future dates).

Automatically chooses the right units (seconds, minutes, etc) to format a time interval.

Examples:

  • just now
  • 45s
  • 5m
  • 15 minutes ago
  • 3 hours ago
  • in 2 months
  • in 5 years
  • …

For React users, there's a React version — See Demo

This is a readme for version 2.x. For older versions, see version 1.x readme. For migrating from version 1.x to version 2.x, see a migration guide.

Install

npm install javascript-time-ago --save

If you're not using a bundler then use a standalone version from a CDN.

Use

import TimeAgo from 'javascript-time-ago'

// English.
import en from 'javascript-time-ago/locale/en'

TimeAgo.addDefaultLocale(en)

// Create formatter (English).
const timeAgo = new TimeAgo('en-US')

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

timeAgo.format(Date.now() - 60 * 1000)
// "1 minute ago"

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

timeAgo.format(Date.now() - 24 * 60 * 60 * 1000)
// "1 day ago"

Locales

This library includes date/time formatting rules and labels for any language.

No languages are loaded default: a developer must manually choose which languages should be loaded. Languages should be imported from javascript-time-ago/locale and then added via TimeAgo.addLocale() or TimeAgo.addDefaultLocale().

The locale argument of new TimeAgo(locale) constructor is matched against the list of added languages, and the first matching one is used. For example, locales "en-US" and "en-GB" both match "en" language. If none of the added languages match the locale, the "default language" is used. If the "default language" hasn't been added, an error is thrown.

The "default language" is "en" by default, and can be set either by calling addDefaultLocale():

import ru from 'javascript-time-ago/locale/ru'
import de from 'javascript-time-ago/locale/de'
import es from 'javascript-time-ago/locale/es'

TimeAgo.addLocale(ru)
TimeAgo.addLocale(de)
TimeAgo.addDefaultLocale(es)

or by calling setDefaultLocale():

import ru from 'javascript-time-ago/locale/ru'
import de from 'javascript-time-ago/locale/de'
import es from 'javascript-time-ago/locale/es'

TimeAgo.addLocale(ru)
TimeAgo.addLocale(de)
TimeAgo.addLocale(es)

TimeAgo.setDefaultLocale('es')

In some cases, a developer might prefer to specify a list of locales to choose from rather than a single locale:

TimeAgo.addDefaultLocale(en)
TimeAgo.addLocale(de)

// "de" language will be used, as it's the first one to match.
new TimeAgo(['ru-RU', 'de-DE', 'en-US'])

An example of using Russian language:

import TimeAgo from 'javascript-time-ago'

// Russian.
import ru from 'javascript-time-ago/locale/ru'

TimeAgo.addDefaultLocale(ru)

const timeAgo = new TimeAgo('ru-RU')

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

timeAgo.format(Date.now() - 60 * 1000)
// "1 минуту назад"

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

timeAgo.format(Date.now() - 24 * 60 * 60 * 1000)
// "1 день назад"

Styles

This library allows for any custom logic for formatting time intervals:

  • What scale should be used for measuring time intervals: should it be precise down to the second, or should it only measure it up to a minute, or should it start from being more precise when time intervals are small and then gradually decrease its precision as time intervals get longer.

  • What labels should be used: should it use the standard built-in labels for the languages ("... minutes ago", "... min. ago", "...m"), or should it use custom ones, or should it skip using relative time labels in some cases and instead output something like "Dec 11, 2015".

Such configuration comes under the name of "style".

While a completely custom "style" could be supplied, this library comes with several built-in "styles" that some people might find useful.

Following is the list of built-in "styles".

Round

Rounds the time up to the closest time measurement unit (second, minute, hour, etc).

timeAgo.format(Date.now(), 'round')
// 0 seconds ago → "just now"

timeAgo.format(Date.now() - 1 * 1000, 'round')
// 1 second ago → "1 second ago"

timeAgo.format(Date.now() - 29 * 1000, 'round')
// 29 seconds ago → "29 seconds ago"

timeAgo.format(Date.now() - 30 * 1000, 'round')
// 30 seconds ago → "1 minute ago"

timeAgo.format(Date.now() - 1.5 * 60 * 1000, 'round')
// 1.5 minutes ago → "2 minutes ago"
  • just now
  • 1 second ago
  • 2 seconds ago
  • …
  • 59 seconds ago
  • 1 minute ago
  • 2 minutes ago
  • …
  • 59 minutes ago
  • 1 hour ago
  • 2 hours ago
  • …
  • 23 hours ago
  • 1 day ago
  • 2 days ago
  • …
  • 6 days ago
  • 1 week ago
  • 2 weeks ago
  • 3 weeks ago
  • 1 month ago
  • 2 months ago
  • …
  • 11 months ago
  • 1 year ago
  • 2 years ago
  • …

Round (minute)

Same as "round" style but without seconds. This is the default style.

timeAgo.format(Date.now(), 'round-minute')
// 0 seconds ago → "just now"

timeAgo.format(Date.now() - 29 * 1000, 'round-minute')
// 29 seconds ago → "just now"

timeAgo.format(Date.now() - 30 * 1000, 'round-minute')
// 30 seconds ago → "1 minute ago"

// The rest is same as "round" style.
  • just now
  • 1 minute ago
  • 2 minutes ago
  • …

Mini

Same as "round" style but as short as possible and without " ago". Also, doesn't include "weeks".

timeAgo.format(new Date(), 'mini')
// 0 seconds ago → "0s"

timeAgo.format(new Date() - 1 * 1000, 'mini')
// 1 second ago → "1s"

timeAgo.format(Date.now() - 2 * 60 * 1000, 'mini')
// 2 minutes ago → "2m"

timeAgo.format(Date.now() - 3 * 60 * 60 * 1000, 'mini')
// 3 hours ago → "3h"

timeAgo.format(Date.now() - 4 * 24 * 60 * 60 * 1000, 'mini')
// 4 days ago → "4d"

timeAgo.format(Date.now() - 23 * 24 * 60 * 60 * 1000, 'mini')
// 23 days ago → "23d"

timeAgo.format(Date.now() - 5 * 30 * 24 * 60 * 60 * 1000, 'mini')
// 5 months ago → "5mo"

timeAgo.format(Date.now() - 12 * 30 * 24 * 60 * 60 * 1000, 'mini')
// 1 year ago → "1yr"

For best compatibility, mini.json labels should be defined for a locale, otherwise you might end up with labels like "-1m" for "one minute ago" for some languages. Send mini.json pull requests for the missing languages if you speak those.

Mini (now)

Same as "mini" style but outputs "now" instead of "0s".

timeAgo.format(new Date(), 'mini-now')
// 0 seconds ago → "now"

timeAgo.format(new Date() - 1 * 1000, 'mini-now')
// 1 second ago → "1s"

// The rest is same as "mini" style.

Mini (minute)

Same as "mini" style but without seconds (starts with minutes).

timeAgo.format(new Date(), 'mini-minute')
// 0 seconds ago → "0m"

timeAgo.format(new Date() - 29 * 1000, 'mini-minute')
// 29 seconds ago → "0m"

timeAgo.format(new Date() - 30 * 1000, 'mini-minute')
// 30 seconds ago → "1m"

// The rest is same as "mini" style.

Mini (minute-now)

Same as "mini-minute" style but outputs "now" instead of "0m".

timeAgo.format(new Date(), 'mini-minute-now')
// 0 seconds ago → "now"

timeAgo.format(new Date() - 29 * 1000, 'mini-minute-now')
// 29 seconds ago → "now"

timeAgo.format(new Date() - 30 * 1000, 'mini-minute-now')
// 30 seconds ago → "1m"

// The rest is same as "mini" style.

Twitter

Mimics Twitter style of "time ago" labels ("1s", "2m", "3h", "Mar 4", "Apr 5, 2012")

timeAgo.format(new Date(), 'twitter')
// 0 seconds ago → "0s"

timeAgo.format(new Date() - 1 * 1000, 'twitter')
// 1 second ago → "1s"

timeAgo.format(Date.now() - 2 * 60 * 1000, 'twitter')
// 2 minutes ago → "2m"

timeAgo.format(Date.now() - 3 * 60 * 60 * 1000, 'twitter')
// 3 hours ago → "3h"

timeAgo.format(Date.now() - 4 * 24 * 60 * 60 * 1000, 'twitter')
// More than 24 hours ago → `month/day` ("Mar 4")

timeAgo.format(Date.now() - 364 * 24 * 60 * 60 * 1000, 'twitter')
// Another year → `month/day/year` ("Mar 5, 2017")

"twitter" style uses Intl for formatting day/month/year labels. If Intl is not available (for example, in Internet Explorer), it falls back to day/month/year labels: "1d", "1mo", "1yr".

For best compatibility, mini.json labels should be defined for a locale. Send pull requests for the missing ones.

Twitter (now)

Same as "twitter" style but outputs "now" instead of "0s".

timeAgo.format(new Date(), 'twitter-now')
// 0 seconds ago → "now"

timeAgo.format(new Date() - 1 * 1000, 'twitter-now')
// 1 second ago → "1s"

// The rest is same as "twitter" style.

Twitter (minute)

Same as "twitter" style but without seconds (starts with minutes).

timeAgo.format(new Date(), 'twitter-minute')
// 0 seconds ago → "0m"

timeAgo.format(new Date() - 29 * 1000, 'twitter-minute')
// 29 seconds ago → "0m"

timeAgo.format(new Date() - 30 * 1000, 'twitter-minute')
// 30 seconds ago → "1m"

// The rest is same as "twitter" style.

Twitter (minute-now)

Same as "twitter-minute" style but outputs "now" instead of "0m".

timeAgo.format(new Date(), 'twitter-minute-now')
// 0 seconds ago → "now"

timeAgo.format(new Date() - 29 * 1000, 'twitter-minute-now')
// 29 seconds ago → "now"

timeAgo.format(new Date() - 30 * 1000, 'twitter-minute-now')
// 30 seconds ago → "1m"

// The rest is same as "twitter" style.

Twitter (first minute)

Same as "twitter" style but doesn't output anything before the first minute.

timeAgo.format(new Date(), 'twitter-first-minute')
// 0 seconds ago → ""

timeAgo.format(new Date() - 29 * 1000, 'twitter-first-minute')
// 29 seconds ago → ""

timeAgo.format(new Date() - 30 * 1000, 'twitter-first-minute')
// 30 seconds ago → "1m"

// The rest is same as "twitter" style.

Custom

A custom "style" object may be passed as a second parameter to .format(date, style), a style being an object defining labels and steps.

Labels

labels should be the name of the time labels variant that will be used for generating output. When not defined, is set to "long" by default.

labels can also be an array of such time label variant names, in which case each one of them is tried until a supported one is found. For example, for labels: ["mini", "short"] it will search for "mini" labels first and then fall back to "short" labels if "mini" labels aren't defined for the language.

"long", "short" and "narrow" time labels are always present for each language, because they're provided by CLDR. long is the normal one, short is an abbreviated version of long, narrow is supposed to be shorter than short but ends up just being weird: it's either equal to short or is, for example, "-1 d." for "1 day ago" in Russian.

Other time labels like "now" and "mini" are only defined for a small subset of languages. Send your pull requests for the missing ones.

New labels can be added by calling TimeAgo.addLabels() function.

import TimeAgo from 'javascript-time-ago'
import en from 'javascript-time-ago/locale/en'
import { round } from 'javascript-time-ago/steps'

TimeAgo.addDefaultLocale(en)

const customLabels = {
  second: {
    past: {
      one: "{0} second earlier",
      other: "{0} seconds earlier"
    },
    future: {
      one: "{0} second later",
      other: "{0} seconds later"
    }
  },
  ...
}

TimeAgo.addLabels('en', 'custom', customLabels)

const timeAgo = new TimeAgo('en-US')

const customStyle = {
  steps: round,
  labels: 'custom'
}

timeAgo.format(Date.now() - 10 * 1000, customStyle)
// "10 seconds earlier"

Steps

Time interval measurement "steps".

Each "step" is tried until the last matching one is found, and that "step" is then used to generate the output. If no matching step was found, then an empty string is returned.

An example of "round" style steps:

[
  {
    // "second" labels are used for formatting the output.
    formatAs: 'second'
  },
  {
    // This step is effective starting from 59.5 seconds.
    minTime: 60,
    // "minute" labels are used for formatting the output.
    formatAs: 'minute'
  },
  {
    // This step is effective starting from 59.5 minutes.
    minTime: 60 * 60,
    // "hour" labels are used for formatting the output.
    formatAs: 'hour'
  },
  …
]

A step can be described by:

minTime

A minimum time interval (in seconds) required for a step, meaning that minTime controls the progression from one step to another. Every step must define a minTime in one way or another. The first step's minTime is 0 by default.

If a step is defined by formatAs, and its previous step is also defined by formatAs, then such step's minTime, if not specified, is calculated automatically according to the selected "rounding". For example, if the previous step is { formatAs: 'second' } and the current step is { formatAs: 'minute' } then the current step's minTime is automatically calculated as 59.5 when round is "round" (default), and 60 when round is "floor".

While minTime is usually a number, it could also be a function returning a number in order to support unusual cases like absolute date formatting in "twitter" style.

minTime(
  date: number,        // The date argument, converted to a timestamp.
  {
    future: boolean,   // Is `true` if `date > now`, or if `date === now`
                       // and `future: true` option was passed to `.format()`.

    getMinTimeForUnit(unit: string, prevUnit: string?): number?
                       // Returns the `minTime` for a transition from a
                       // previous step with `formatAs: prevUnit` to a
                       // step with `formatAs: unit`.
                       // For example, if the previous step is `formatAs: "second"`,
                       // then `getMinTimeForUnit('minute')` returns `59.5`
                       // when `round` is "round", and `60` when `round` is "floor".
                       // A developer can also explicitly specify the previous step's unit:
                       // `getMinTimeForUnit('minute', 'second')`.
                       // Returns `undefined` if `unit` or `prevUnit` are not supported.
  }
): number
formatAs

A time measurement unit, the labels for which are used to generate the output of a step. If the time unit isn't supported by the language, then the step is ignored. The time units supported in all languages are: second, minute, hour, day, week, month, quarter, year. For some languages, this library also defines now unit ("just now").

format()

Alternatively to formatAs, a step may specify a format() function:

format(
  date: number,        // The date argument, converted to a timestamp.
  locale: string,      // The currently selected language. Example: "en".
  {
    formatAs(unit: string, value: number): string,
                       // A function that could be used to format `value` in `unit`s.
                       // Example: `formatAs('second', -2)`
                       // Outputs: "2 seconds ago"

    now: number,       // The current date timestamp.

    future: boolean    // Is `true` if `date > now`, or if `date === now`
                       // and `future: true` option was passed to `.format()`.
  }
): string?
Time unit constants

/steps export provides some utility time unit constants that could be used to calculate minTime values when defining custom steps:

import { minute, hour, day, week, month, year } from 'javascript-time-ago/steps'

// In seconds
minute === 60
hour === 60 * 60
day === 24 * 60 * 60
...

const customSteps = [{
  minTime: 5 * minute,
  ...
}]

Rounding

Controls the rounding of an amount of time units.

The default round is "round" which equals to Math.round().

  • 0.1 sec. ago → "0 sec. ago"
  • 0.4 sec. ago → "0 sec. ago"
  • 0.5 sec. ago → "1 sec. ago"
  • 0.9 sec. ago → "1 sec. ago"
  • 1.0 sec. ago → "1 sec. ago"

Some people asked for an alternative rounding method, so there's also round: "floor" which equals to Math.floor().

  • 0.1 sec. ago → "0 sec. ago"
  • 0.4 sec. ago → "0 sec. ago"
  • 0.5 sec. ago → "0 sec. ago"
  • 0.9 sec. ago → "0 sec. ago"
  • 1.0 sec. ago → "1 sec. ago"

A developer can choose the rounding method by passing round option to timeAgo.format(date, [style], options). The default rounding can also be set for a style by setting its round property.

Future

When given future dates, .format() produces the corresponding output.

timeAgo.format(Date.now() + 5 * 60 * 1000)
// "in 5 minutes"

Zero time interval is a special case: by default, it's formatted in past time. To format zero time interval in future time, pass future: true option to .format().

// Without `future: true` option:

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

timeAgo.format(Date.now() + 5 * 60 * 1000)
// "in 5 minutes"

// With `future: true` option:

timeAgo.format(Date.now(), { future: true })
// "in a moment"

timeAgo.format(Date.now() + 5 * 60 * 1000, { future: true })
// "in 5 minutes" (no difference)

Now

The .format() function accepts an optional now: number option: it can be used in tests to specify the exact "base" timestamp relative to which the time interval will be calculated.

timeAgo.format(60 * 1000, { now: 0 })
// "1 minute ago"

Update Interval

When speaking of good User Experience ("UX"), a formatted relative date, once rendered, should be constantly refreshed. And for that, the application should know how often should it refresh the formatted date. For that, each step should provide an update interval.

When a step has formatAs configured, then getTimeToNextUpdate() function is created automatically for it. Otherwise, a developer should supply their own getTimeToNextUpdate() function for a step.

getTimeToNextUpdate(
  date: number, // The date argument, converted to a timestamp.
  {
    getTimeToNextUpdateForUnit(unit: string): number?,
                       // Returns "time to next update" for a time unit.
                       // This is what the library calls internally
                       // when `formatAs` is configured for a `step`.
                       // Example: `getTimeToNextUpdateForUnit('minute')`.
                       // Can return `undefined` in edge cases:
                       // for example, when `unit` is "now".

    now: number,       // The current date timestamp.

    future: boolean    // Is `true` if `date > now`, or if `date === now`
                       // and `future: true` option was passed to `.format()`.
  }
): number?

The application can then pass getTimeToNextUpdate: true option to .format() to get the best time to update the relative date label.

const timeAgo = new TimeAgo('en-US')

let updateTimer

function render() {
  // Format the date.
  const [formattedDate, timeToNextUpdate] = timeAgo.format(date, {
    getTimeToNextUpdate: true
  })
  // Update the label.
  setFormattedDate(formattedDate)
  // Schedule next render.
  // `timeToNextUpdate` may be `undefined`, so provide a sensible default.
  updateTimer = setTimeout(render, getSafeTimeoutInterval(timeToNextUpdate || 60 * 1000))
}

// `setTimeout()` has a bug where it fires immediately
// when the interval is longer than about `24.85` days.
// https://stackoverflow.com/questions/3468607/why-does-settimeout-break-for-large-millisecond-delay-values
const SET_TIMEOUT_MAX_SAFE_INTERVAL = 2147483647
function getSafeTimeoutInterval(interval) {
  return Math.min(interval, SET_TIMEOUT_MAX_SAFE_INTERVAL)
}

Notice that setTimeout() has a bug where it fires immediately when the interval is longer than about 24.85 days, so the interval should not exceed that number. Otherwise, it will result in an infinite recursion.

Localization internals

This library uses an Intl.RelativeTimeFormat polyfill under the hood. The polyfill is only 3.5 kB in size so it won't affect the total bundle size.

Some people have requested the ability to use native Intl.RelativeTimeFormat and Intl.PluralRules instead of the polyfills: in this case, pass polyfill: false option when creating a TimeAgo instance.

new TimeAgo('en-US', { polyfill: false })

React

For React users, there's a React version — See Demo.

CDN

One can use any npm CDN service, e.g. unpkg.com or jsdelivr.com

<!-- Example `[version]`: `2.x` -->
<script src="https://unpkg.com/javascript-time-ago@[version]/bundle/javascript-time-ago.js"></script>

<script>
  TimeAgo.addDefaultLocale({
    locale: 'en',
    now: {
      now: {
        current: "now",
        future: "in a moment",
        past: "just now"
      }
    },
    long: {
      year: {
        past: {
          one: "{0} year ago",
          other: "{0} years ago"
        },
        future: {
          one: "in {0} year",
          other: "in {0} years"
        }
      },
      ...
    }
  })
</script>

<script>
  alert(new TimeAgo('en-US').format(new Date()))
</script>

Intl

(this is an "advanced" section)

Intl global object is not required for this library, but, for example, if you choose to use the built-in twitter style then it will format longer intervals as 1d, 1mo, 1yr instead of Apr 10 or Apr 10, 2019 if Intl is not available: that's because it uses Intl.DateTimeFormat for formatting absolute dates.

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.

An example of 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(...)

TypeScript

This library comes with TypeScript "typings". If you happen to find any bugs in those, create an issue.

Tests

This component comes with a 100% code coverage.

To run tests:

npm test

To generate a code coverage report:

npm run test-coverage

The code coverage report can be viewed by opening ./coverage/lcov-report/index.html.

The handlebars@4.5.3 workaround in devDependencies is for the test coverage to not produce empty reports:

Handlebars: Access has been denied to resolve the property "statements" because it is not an "own property" of its parent.
You can add a runtime option to disable the check or this warning:
See https://handlebarsjs.com/api-reference/runtime-options.html#options-to-control-prototype-access for details

GitHub

On March 9th, 2020, GitHub, Inc. silently banned my account (erasing all my repos, issues and comments, even in my employer's private repos) without any notice or explanation. Because of that, all source codes had to be promptly moved to GitLab. The GitHub repo is now only used as a backup (you can star the repo there too), and the primary repo is now the GitLab one. Issues can be reported in any repo.

License

MIT

Readme

Keywords

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Install

npm i javascript-time-ago

Repository

gitlab.com/catamphetamine/javascript-time-ago

Homepage

gitlab.com/catamphetamine/javascript-time-ago#readme

Weekly Downloads

501,067

Version

2.5.11

License

MIT

Unpacked Size

4.45 MB

Total Files

1489

Last publish

Collaborators

  • catamphetamine
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