fmt-tag

fmt-tag

Format template literals.

Installation

This package is distributed via npm:

npm install fmt-tag

Motivation

Template literals and template tags provide a unique API to build tools around strings. What started as a fun blog post about template tags ended up being this full-fledged library that might hopefully be useful to someone!

Usage

You can use this library either as an ES module or a CommonJS package:

import fmt from "fmt-tag";

- or -

const fmt = require("fmt-tag");

Please note that this library uses extensively Intl, which is not supported on older browsers (https://caniuse.com/?search=Intl) or Node versions < 16.

You can tag any template literal and append formatting hints right after interpolations to apply specific formatting to that substitutive value.

const name = "Alice";
const money = 20;

console.log(fmt`${name} has ${money}:c(USD) in her pocket!`);
// "Alice has $20 in her pocket!"

The formatting uses the host's default language settings. You can also pass in a specific locale via fmt.use(locale).

fmt.use(locale: string)

Sets a locale to be used when formatting template literals. By default, the formatting will use the host's default language settings.

Formatters

There are a few formatters available (more to come!).

Currency

Key	Options
:c	Any valid currency symbol (e.g. :c(USD), :c(EUR), ...)

Date

Key	Options
:d	- :d(DD-MM-YYYY) => 01/01/1970 - :d(DD-mm-YYYY) => 1 Jan 1970 - :d(DD-mmm-YYYY) => 1 January 1970 - :d(ddd-mmm-YYYY) => Thursday, 1 January 1970

Number

Key	Options
:n	Number of digits (e.g. :n(2) => 42.00)

Relative Time

Key	Options
:r	RelativeTimeUnit (e.g. ${-1}:r(weeks) => last week)

String

Key	Options
:s (default)	- :s => No transformation - :s(U) => Uppercase - :s(l) => lowercase

Time

Key	Options
:t	- :t(HH:mm) => 06:56 - :t(HH:mm aa) => 06:56 am - :t(HH:mm:ss) => 06:56:07 - :t(HH:mm:ss aa) => 06:56:07 am - :t(HH:mm:ss TZ) => 06:56:07 UTC - :t(HH:mm:ss TZ+) => 06:56:07 Coordinated Universal Time

Acknowledgements

Thanks to Jack Hsu and his article on implementing an internationalization library using template literals (https://jaysoo.ca/2014/03/20/i18n-with-es2015-template-literals/) for the inspiration!

License

MIT