Local Time makes it easy to display times and dates to users in their local time. Its Rails helpers render <time> elements in UTC (making them cache friendly), and its JavaScript component immediately converts those elements from UTC to the browser's local time.

1. Add gem 'local_time' to your Gemfile.

2. Include local-time.js in your application's JavaScript bundle.

   Using the asset pipeline:

   //= require local-time

   Using the local-time npm package:

   import LocalTime from "local-time"
   LocalTime.start()

> comment.created_at
"Wed, 27 Nov 2013 18:43:22 EST -0500"

<%= local_time(comment.created_at) %>

Renders:

<time data-format="%B %e, %Y %l:%M%P"
      data-local="time"
      datetime="2013-11-27T23:43:22Z">November 27, 2013 11:43pm</time>

And is converted client-side to:

<time data-format="%B %e, %Y %l:%M%P"
      data-local="time"
      datetime="2013-11-27T23:43:22Z"
      title="November 27, 2013 6:43pm EDT"
      data-localized="true">November 27, 2013 6:43pm</time>

(Line breaks added for readability)

<%= local_time(time) %>

Format with a strftime string (default format shown here)

<%= local_time(time, '%B %e, %Y %l:%M%P') %>

Alias for local_time with a month-formatted default

<%= local_date(time, '%B %e, %Y') %>

To set attributes on the time tag, pass a hash as the second argument with a :format key and your attributes.

<%= local_time(time, format: '%B %e, %Y %l:%M%P', class: 'my-time') %>

To use a strftime format already defined in your app, pass a symbol as the format.

<%= local_time(date, :long) %>

I18n.t("time.formats.#{format}"), I18n.t("date.formats.#{format}"), Time::DATE_FORMATS[format], and Date::DATE_FORMATS[format] will be scanned (in that order) for your format.

Note: The included strftime JavaScript implementation is not 100% complete. It supports the following directives: %a %A %b %B %c %d %e %H %I %l %m %M %p %P %S %w %y %Y %Z

<%= local_time_ago(time) %>

Displays the relative amount of time passed. With age, the descriptions transition from {quantity of seconds, minutes, or hours} to {date + time} to {date}. The <time> elements are updated every 60 seconds.

Examples (in quotes):

• Recent: "a second ago", "32 seconds ago", "an hour ago", "14 hours ago"
• Yesterday: "yesterday at 5:22pm"
• This week: "Tuesday at 12:48am"
• This year: "on Nov 17"
• Last year: "on Jan 31, 2012"

Preset time and date formats that vary with age. The available types are date, time-ago, time-or-date, and weekday. Like the local_time helper, :type can be passed a string or in an options hash.

<%= local_relative_time(time, 'weekday') %>
<%= local_relative_time(time, type: 'time-or-date') %>

Available :type options

• date Includes the year unless it's current. "Apr 11" or "Apr 11, 2013"
• time-ago See above. local_time_ago calls local_relative_time with this :type option.
• time-or-date Displays the time if it occurs today or the date if not. "3:26pm" or "Apr 11"
• weekday Displays "Today", "Yesterday", or the weekday (e.g. Wednesday) if the time is within a week of today.
• weekday-or-date Displays the weekday if it occurs within a week or the date if not. "Yesterday" or "Apr 11"

Internationalization (I18n)

Local Time includes a set of default en translations which can be updated directly. Or, you can provide an entirely new set in a different locale:

LocalTime.config.i18n["es"] = {
  date: {
    dayNames: [ … ],
    monthNames: [ … ],
    …
  },
  time: {
    …
  },
  datetime: {
    …
  }
}

LocalTime.config.locale = "es"

2.0.1 (June 6, 2018)

• Add aria-label attribute to improve accessibility

2.0.0 (August 7, 2017)

• Add internationalization (I18n) API
• Switch to MutationObserver instead of listening for various DOM, Turbolinks, and jQuery events
• Publish JavaScript module on npm
• Drop coffee-rails gem dependency
• Renamed local_time.js to local-time.js

1.0.3

• Improve %Z time zone parsing
• Use Blade runner for JavaScript tests

1.0.2 (February 3, 2015)

• Fix displaying future relative dates [Cezary Baginski]

1.0.1 (December 3, 2014)

• Added weekday-or-date option [Chew Choon Keat]

1.0.0 (April 12, 2014)

• Added local_relative_time helper with several built in types
• Allow :format (and :type) option as a bare string or value in hash
• Added relativeDate, relativeTimeOrDate, relativeWeekday and run to the API
• Dropped ineffective popstate event listener
• Now in use at Basecamp

0.3.0 (February 9, 2014)

• Allow :format option lookup in I18n or DATE_FORMATS hashes [Paul Dobbins]
• Expose public API to JavaScript helpers

0.2.0 (December 10, 2013)

• Prefer textContent over innerText for Firefox compatibility
• Added options argument to local_time_ago helper

0.1.0 (November 29, 2013)

• Initial release.