Repeat an array

Concatenate an array with itself n times.

JavaScript Version 1.0.0 · MIT · .md

function repeatArray({ values, times }) { return Array(times).fill(values).flat(); }

Input & expected output

{
  "values": [
    "a",
    "b"
  ],
  "times": 3
}

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

The edge case

{
  "values": [
    1
  ],
  "times": 0
}

[]

Know the limits

• flat() flattens one level only, so nested arrays inside values stay nested.
• The lab caps the result at 1,000 items before allocating.

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.