3.0.2 • Public • Published

Local Time

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. Run bundle install

  3. Run bin/importmap pin local-time to add the local-time npm package

  4. Add this to app/javascript/application.js

    import LocalTime from "local-time"


  1. Add gem "local_time" to your Gemfile.

  2. Run bundle install

  3. Run yarn add local-time

  4. Add this to app/javascript/packs/application.js

    import LocalTime from "local-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>

And is converted client-side to:

<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) %>

When using the local_time helper 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.

When using the local_date helper, I18n.t("date.formats.#{format}"), I18n.t("time.formats.#{format}"), Date::DATE_FORMATS[format], and Time::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 helpers

<%= 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 helpers

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"

24-hour time formatting Local Time supports 24-hour time formats out of the box.

To use this feature, configure the library to favor data-format24 over data-format attributes:

LocalTime.config.useFormat24 = true

The library will now default to using the data-format24 attribute on <time> elements for formatting. But it will still fall back to data-format if data-format24 is not provided.

The included Rails helpers will automatically look for 24h variants of named formats. They will search for #{name}_24h in the same places the regular name is looked up.

This is an example of what your app configuration might look like:

Time::DATE_FORMATS[:simple] = "%-l:%M%P"
Time::DATE_FORMATS[:simple_24h] = "%H:%M"

When :type is set to time-ago, the format is obtained from the I18n configuration.

In practice, you might set config.useFormat24 to true or false depending on the current user's configuration, before rendering any <time> elements.


Please read CONTRIBUTING.md.




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