Datetime Formatting

Basic Usage

You can localize the datetime with your definition formats.

Datetime formats the below:

const datetimeFormats = {
  'en-US': {
    short: {
      year: 'numeric', month: 'short', day: 'numeric'
    },
    long: {
      year: 'numeric', month: 'short', day: 'numeric',
      weekday: 'short', hour: 'numeric', minute: 'numeric'
    }
  },
  'ja-JP': {
    short: {
      year: 'numeric', month: 'short', day: 'numeric'
    },
    long: {
      year: 'numeric', month: 'short', day: 'numeric',
      weekday: 'short', hour: 'numeric', minute: 'numeric', hour12: true
    }
  }
}

As seen above, you can define named datetime format (e.g. short, long, etc), and you need to use the options with ECMA-402 Intl.DateTimeFormat

After that, when using the locale messages, you need to specify the datetimeFormats option of createI18n:

const i18n = createI18n({
  datetimeFormats
})

To localize DateTime value with Vue I18n, use the $d.

NOTE

$d has some overloads. About these overloads, see the API Reference

NOTE

Some ways to support localize are:

  • $d (for Legacy API mode & Composition API mode)
  • built-in DatetimeFormat component (i18n-d)
  • exported d from useI18n (for Composition API mode)

The following is an example of the use of $d in a template:

<p>{{ $d(new Date(), 'short') }}</p>
<p>{{ $d(new Date(), 'long', 'ja-JP') }}</p>

The first argument is datetime able value (e.g. Date, timestamp) as a parameter, and the second argument is datetime format name as a parameter. The last argument locale value as a parameter.

As result the below:

<p>Apr 19, 2017</p>
<p>2017年4月19日(水) 午前2:19</p>

Custom Formatting

NOTE

Not supported IE, due to no support Intl.DateTimeForamt#formatToParts in IE

If you want to use it, you need to use polyfill

$d returns resulting string with fully formatted datetime, which can only be used as a whole. In situations when you need to style some part of the formatted datetime (like fraction digits), $d is not enough. In such cases DatetimeFormat component (i18n-d) will be of help.

With a minimum set of properties, i18n-d generates the same output as $d, wrapped into configured DOM element.

The following template:

<i18n-d tag="p" :value="new Date()"></i18n-d>
<i18n-d tag="p" :value="new Date()" format="long"></i18n-d>
<i18n-d tag="p" :value="new Date()" format="long" locale="ja-JP-u-ca-japanese"></i18n-d>

DatetimeFormat component has some props.

The tag is the property to set the tag.

The value prop is a property to set the datetime able value to be formatted.

The format prop is a property to which the format defined by the datetimeFormats option of createI18n can be set.

The locale prop is a property to set the locale. It's localized with the locale specified by this prop instead of the one specified with the locale option of createI18n.

Will produce the below output:

<p>11/3/2020</p>
<p>11/03/2020, 02:35:31 AM</p>
<p>令和2年11月3日火曜日 午前2:35:31 日本標準時</p>

But the real power of this component comes into play when it is used with scoped slots.

Let’s say there is a requirement to render the era part of the datetime with a bolder font. This can be achieved by specifying era scoped slot element:

<i18n-d tag="span" :value="new Date()" locale="ja-JP-u-ca-japanese" :format="{ key: 'long', era: 'narrow' }">
  <template #era="props">
    <span style="color: green">{{ props.era }}</span>
  </template>
</i18n-d>

Template above will result in the following HTML:

<span><span style="color: green;">R</span>2年11月3日火曜日 午前2:35:31 日本標準時</span>

It is possible to specify multiple scoped slots at the same time:

<i18n-d tag="span" :value="new Date()" locale="ja-JP-u-ca-japanese" :format="{ key: 'long', era: 'narrow' }">
  <template #era="props">
    <span style="color: green">{{ props.era }}</span>
  </template>
  <template #literal="props">
    <span style="color: green">{{ props.literal }}</span>
  </template>
</i18n-d>

(this resulting HTML was formatted for better readability)

<span>
  <span style="color: green;">R</span>2
  <span style="color: green;"></span>11
  <span style="color: green;"></span>3
  <span style="color: green;"></span>火曜日
  <span style="color: green;"> </span>午前3
  <span style="color: green;">:</span>09
  <span style="color: green;">:</span>56
  <span style="color: green;"> </span>日本標準時
</span>

NOTE

Full list of the supported scoped slots as well as other i18n-d, properties can be found on API Reference.