filter-map

Array utility to help writing filter/map separately without struggling with reduce

Description

Have you ever experienced writing filtering and mapping over an array at the same time? will you go for this way:

const res = [1, 2, 3, 4, 5].filter(it => it % 2 === 0).map(it => it ** 3) // Two iterations
console.log(res) // [8, 64]

Then I guess you have a colleague that adds a review comment to use Array's reduce to perform less iterations. Why bother writing it with reduce when you can do:

const res = [1, 2, 3, 4, 5].filterMap(it => it % 2 === 0, it => it ** 3) // One iteration
console.log(res) // [8, 64]

Installing

npm i -S @jamiri/filter-map

or

yarn add @jamiri/filter-map

Importing

Nodejs

require('filter-map')
console.log([1, 2, 3].filterMap(x => x > 1, x => x * 3))

Webpack

import 'filter-map'
console.log([1, 2, 3].filterMap(x => x > 1, x => x * 3))

Api

Upon requireing/importing the package following functions are added to the array prototype

filterMap(filterFn, mapFn)
mapFilter(mapFn, filterFn)

These are now available on instances of arrays i.e. all arrays from there on.