Flatten an array of arbitrarily nested arrays of integers into a flat array of integers.

readme.md

Conversio Code Test

Github repo here

flatten-array.js

module.exports = flattenArray

/**
 * Flatten a multi-dimensional array.
 *
 * @param {Number[]} array
 */
function flattenArray(array) {
  return array.reduce((result, el) => {
    // If the element is an array, continue to flatten it.
    if (Array.isArray(el)) {
      return result.concat(flattenArray(el))
    }

    // Do not accept non integer elements
    if (!Number.isInteger(el)) {
      return result
    }

    // Otherwise, we now have the element, push it into the result.
    result.push(el)
    return result
  }, [])
}

flattenArraySpec.js

// Spec file for flatten array method.
const flattenArray = require('../index')

describe('flattenArray method', () => {
  it('should flatten an abritrary array of nested arrays', () => {
    const array = [1, [2, 3], 4, [5, [6]]]
    const flatArray = flattenArray(array)
    const expectedArray = [1, 2, 3, 4, 5, 6]
    expect(flatArray).toEqual(expectedArray)
  })

  it('should return only an array of integers', () => {
    const array = [1, [2, 3], 4.05, ['5', [6]]]
    const flatArray = flattenArray(array)
    const expectedArray = [1, 2, 3, 6]
    expect(flatArray).toEqual(expectedArray)
  })
})