Add format.timeFormatter to get raw access to the formatter

[cibernox]

The reason behind this PR is that I need to call formatter.formatToParts instead of simply formatter.format.

I'm happy to change the approach if you think some other approach is more flexible while allowing to call formatToParts.

If this approach seems ok I can add the same method for the dateFormatter too.

Fixes #30

[kaisermann]

Hey! Thanks for the PR.

What do you think about exporting the getXxxxxFormatter methods?

// index.ts
export {
  getDateFormatter,
  getNumberFormatter,
  getTimeFormatter,
  getMessageFormatter,
} from './includes/formatters'

Then you would be able to pass a locale and all the other parameters you want.

[cibernox]

@kaisermann I'm ok with that, but unless I'm mistaken if the user changes the selected locale, the app wouldn't be notified the same way they are when using store, right?

For completenes, this is a store I've created that returns a function that knows how to format the time of the next high/low tide

import { t } from "svelte-i18n";

export const formatNextTideDate = derived([t], ([format]) => {
  return (nextTideDate, centerDate) => {
    let centerDateInSeconds = centerDate.getTime() / 1000;
    let nextTideDateInSeconds = nextTideDate.getTime() / 1000;
    if (
      centerDateInSeconds >= nextTideDateInSeconds - FIFTEEN_MINUTES_IN_SECONDS &&
      centerDateInSeconds <= nextTideDateInSeconds + FIFTEEN_MINUTES_IN_SECONDS
    ) {
      return format("tide.now");
    } else {
      return format.time(nextTideDate, { format: 'short' });
    }
  }
});

[kaisermann]

Yeah, being a low-level API, you would need to keep the locale updated. Following your example, it's simple to do that, just also derive from the locale store:

import { t, locale } from '...'

export const customFormatThingie = derived([t, locale], (format, currentLocale) => ....);

Would that help you?

[cibernox]

@kaisermann yeah, that makes sense. I've updated the PR to export the getXxxxxFormatters from the index. I've updated test/client/includes/formatters.test.ts to import the tested utilities from the index, so we're also asserting not only that they work but that they are exposed publicly.

[cibernox]

Any feedback on this one that I should address?

[cibernox]

ping

[kaisermann]

Hey, @cibernox, I'm going to take a look at this PR's code soon. Been busy with the beginning of the year 😁

[kaisermann]

Released on v2.2.0. Added some documentation to the wiki: https://github.com/kaisermann/svelte-i18n/wiki/Methods#low-level-api

[cibernox]

Great, thanks!