Zip multiple arrays

Pair the n-th items of several arrays.

JavaScript Version 1.0.0 · MIT · .md

function zip(arrays) { return Array.from({ length: Math.max(0, ...arrays.map(array => array.length)) }, (_, i) => arrays.map(array => array[i] ?? null)); }

Input & expected output

[
  [
    "[email protected]",
    "[email protected]"
  ],
  [
    "delivered",
    "deferred"
  ]
]

[
  [
    "[email protected]",
    "delivered"
  ],
  [
    "[email protected]",
    "deferred"
  ]
]

The edge case

[
  [
    "a",
    "b"
  ],
  [
    1
  ]
]

[
  [
    "a",
    1
  ],
  [
    "b",
    null
  ]
]

Know the limits

• Missing items become null (undefined in the original) so the result is JSON-representable.
• The original took arrays as separate arguments.

The function above is the implementation used by the lab. The lab validates JSON types and caps size before execution; include equivalent validation when accepting untrusted input in your application.

Keep exploring

• Clone an array — Create a new array without copying the objects inside it.
• Remove duplicate values — Keep the first occurrence of each value, in its original order.
• Flatten a nested array — Turn a nested array into one sequence of values.