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.

Installation

Importmaps

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"
   LocalTime.start()
   document.addEventListener("turbo:morph", () => {
     LocalTime.run()
   })

Webpacker

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"
   LocalTime.start()

Example

> 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)

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"

Configuration

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"

[!NOTE] The "default" keys in the i18n configuration object are used for translations in LocalTime's RelativeTime module. They are not used to determine which format is rendered when none is provided. See https://github.com/basecamp/local_time/issues/128 for details.

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.

Contributing

Please read CONTRIBUTING.md.