ezze/map-fn

Mapping utility functions

map-fn

A set of utility functions to map one type of values to another one with ease.

Installation

pnpm add map-fn -P

Usage

import { createMapFn } from 'map-fn';

type A = 'foo' | 'bar' | 'baz';
type B = 'FOO' | 'BAR' | 'BAZ';

const mapAB = createMapFn<A, B>({
  foo: 'FOO',
  bar: 'BAR'
});

console.log(mapAB('foo')); // 'FOO'
console.log(mapAB('bar')); // 'BAR'

If no corresponding value is provided then MappingError will be thrown:

console.log(mapAB('baz')); // MappingError

There are three options to avoid MappingError in such cases:

1. Provide default value in createMapFn:

   const mapAB = createMapFn<A, B>({
     foo: 'FOO',
     bar: 'BAR'
   }, { defaultValue: 'BAZ' });
   
   console.log(mapAB('baz')); // 'BAZ'

2. Provide default value calling mapping function:

   const mapAB = createMapFn<A, B>({
     foo: 'FOO',
     bar: 'BAR'
   });
   
   console.log(mapAB('baz', { defaultValue: 'BAZ' })); // 'BAZ'

3. Use createMapFnUndefined instead. Please note that output type will be B | undefined (not B):

   const mapAB = createMapFnUndefined<A, B>({
     foo: 'FOO',
     bar: 'BAR'
   });
   
   console.log(mapAB('baz')); // undefined

License

MIT