Compare two arrays

Check the same length and the same items in the same order.

JavaScript Version 1.0.0 · MIT · .md

function isEqual({ a, b }) { return a.length === b.length && a.every((value, i) => Object.is(value, b[i])); }

Input & expected output

{
  "a": [
    1,
    2,
    3
  ],
  "b": [
    1,
    2,
    3
  ]
}

true

The edge case

{
  "a": [
    1,
    2,
    3
  ],
  "b": [
    1,
    2,
    "3"
  ]
}

false

Know the limits

• Shallow comparison with Object.is. The original JSON.stringify variant treats undefined and null alike and depends on key order for nested objects.

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.