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30-seconds-of-code/snippets/bifurcate.md
Mathias Bynens f2e5e26af3 Avoid confusing prototype methods for static methods
Correct: `Array.from()` (it’s a static method)
Incorrect: `Array.join()` (doesn’t exist; it’s a prototype method)

This patch uses the common `#` syntax to denote `.prototype.`.
2018-09-28 15:44:12 -04:00

554 B

bifurcate

Splits values into two groups. If an element in filter is truthy, the corresponding element in the collection belongs to the first group; otherwise, it belongs to the second group.

Use Array.prototype.reduce() and Array.prototype.push() to add elements to groups, based on filter.

const bifurcate = (arr, filter) =>
  arr.reduce((acc, val, i) => (acc[filter[i] ? 0 : 1].push(val), acc), [[], []]);
bifurcate(['beep', 'boop', 'foo', 'bar'], [true, true, false, true]); // [ ['beep', 'boop', 'bar'], ['foo'] ]