array-partition

utility function - partitions array into two arrays, where the first one contains elements for which fn returns a truthy value, and the second one – for which fn returns something falsy (as seen on Enum.partition/2)

Composes nicely with ES6 destructuring assignment

partition(array, predicate(element, index, array))

import partition from 'array-partition';
 
let [even, odd] = partition([1,2,3,4,6,7,9,10], (n) => n % 2 == 0);
// even == [1,3,5,7,9], odd == [2,4,6,8,10]
 
const letters = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','w','x','y','z'];
let [firstThreeLetters, rest] = partition(letters, (el, i) => i < 3);
// firstThreeLetters == ['a','b','c']