flattern.js

// An example of recursive flattering of a given data (potentially multidimensional)

// 1.
// concat all the arrays of a given array and return a new array with a result
const concat = arr => [].concat(...arr)

// recursively flattern a given data into a new array (ES6)
const flattern = el => Array.isArray(el) ? concat(el.map(flattern)) : Array.of(el)

// 2.
// An example of concat before ES6
const concatPreES6 = arr => [].concat.apply([], arr)

// ES6 Flattern and concat in one line
const flatternOne = el => Array.isArray(el) ? [].concat(...el.map(flatternOne)) : Array.of(el)

const data = [
  [1],
  [2, 3],
  [4],
  [
    [5, 6],
    [
      { baa: 'foo', zaaa: 123, sss: { roo: 'moo' } },
      [
        { ba11: 'foo1', zaaa: 123, sss: { roo: 'moo' } },
        { ba22: 'fo2', zaaa: 123, sss: { roo: 'moo' } }
      ],
      [7],
      [8, 9, {sol: '1', col: e => e + 2 }]
    ],
    [
      [10],
      [
        [11, { foo: 'bar', moo: [3,4,5, [6,7]]}],
        [12, 13],
        14
      ],
      15
    ]
  ]
]

const result = flatternOne(data)

console.info(result) 
/**
 * Expected output
 * 
 [ 1,
  2,
  3,
  4,
  5,
  6,
  { baa: 'foo', zaaa: 123, sss: { roo: 'moo' } },
  { ba11: 'foo1', zaaa: 123, sss: { roo: 'moo' } },
  { ba22: 'fo2', zaaa: 123, sss: { roo: 'moo' } },
  7,
  8,
  9,
  { sol: '1', col: [Function: col] },
  10,
  11,
  { foo: 'bar', moo: [ 3, 4, 5, [Array] ] },
  12,
  13,
  14,
  15 ]
 */