@tannin/sprintf

Given a format string, returns string with arguments interpolatation. Arguments can either be provided directly via function arguments spread, or with an array as the second argument.

See: https://en.wikipedia.org/wiki/Printf_format_string

In addition to basic placeholder substitution, the following options a placeholder are implemented:

• Positional index
• Named arguments
• Precision / maximum width (including * precision)
• Type (only the behaviors of f, d, s, and % are applied)

Notably, this excludes:

• Flags
• Minimum width (padding)
• Length

Installation

Using npm as a package manager:

npm install @tannin/sprintf

Otherwise, download a pre-built copy from unpkg:

https://unpkg.com/@tannin/sprintf/dist/sprintf.min.js

Usage

Using positional arguments:

import sprintf from '@tannin/sprintf';

sprintf( 'Hello %s!', 'world' );
// ⇒ 'Hello world!'

Using named arguments:

import sprintf from '@tannin/sprintf';

sprintf( 'Hello %(place)s! From %(name)s.', { place: 'world', name: 'Andrew' } )
// ⇒ 'Hello world! From Andrew.'

Type coercions and default values

When replacing numeric types (%d and %f), values will be coerced to numeric values, and default to 0:

• sprintf( '%d', 123 ) returns '123'
• sprintf( '%d', '123' ) returns '123'
• sprintf( '%d', 'string' ) returns '0'
• sprintf( '%d', false ) returns '0'
• sprintf( '%d', null ) returns '0'
• sprintf( '%d', undefined ) returns '0'

When replacing string types (%s), values will be coerced to strings, and nullish values will be replaced with '':

• sprintf( '%s', 'string' ) returns 'string'
• sprintf( '%s', 0 ) returns '0'
• sprintf( '%s', false ) returns 'false'
• sprintf( '%s', null ) returns ''
• sprintf( '%s', undefined ) returns ''

License

Copyright 2019-2020 Andrew Duthie

Released under the MIT License.