Rails engine for cache-friendly, client-side local time
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Latest commit d8afbee Apr 17, 2017 @javan javan committed on GitHub Merge pull request #67 from bryant1410/master
Fix broken headings in Markdown files


Local Time is a Rails engine with helpers and JavaScript for displaying times and dates to users in their local time. The helpers render a <time> element and the JavaScript swoops in to convert and format. The helper output is ideal for caching since it's always in UTC time.


> comment.created_at
"Wed, 27 Nov 2013 18:43:22 EST -0500"
<%= local_time(comment.created_at) %>


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

When the DOM loads, the content is immediately replaced with a local, formatted time:

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

(Line breaks added for readability)

Time and date helpers

<%= 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

Time ago helper

<%= 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"

Relative time helper

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"


  1. Add gem 'local_time' to your Gemfile.
  2. Run bundle install.
  3. Add //= require local_time to your JavaScript manifest file (usually found at app/assets/javascripts/application.js).

JavaScript events and library compatibility

The included JavaScript does not depend on any frameworks or libraries, and listens for a DOMContentLoaded event to run initially. It also listens on document for page:update if you're using Turbolinks and ajaxSuccess if you're using jQuery. This should catch most cases where new <time> elements have been added to the DOM and process them automatically. If you're adding new elements in another context, trigger time:elapse to process them.

JavaScript API

relativeDate, relativeTimeAgo, relativeTimeOrDate, relativeWeekday, run, and strftime methods are available on the global LocalTime object.

> LocalTime.relativeTimeAgo(new Date(new Date - 60 * 1000 * 5))
"5 minutes ago"

// Process <time> tags. Equivalent to dispatching a "time:elapse" Event.
> LocalTime.run()

> LocalTime.strftime(new Date, "%B %e, %Y %l:%M%P")
"February 9, 2014 12:55pm"

Version History


  • 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.

Build Status

Sauce Test Status