Check if arrays have same contents

JavaScript, Array · Oct 19, 2020

Checks if two arrays contain the same elements regardless of order.

  • Use a for...of loop over a Set created from the values of both arrays.
  • Use Array.prototype.filter() to compare the amount of occurrences of each distinct value in both arrays.
  • Return false if the counts do not match for any element, true otherwise.
const haveSameContents = (a, b) => {
  for (const v of new Set([...a, ...b]))
    if (a.filter(e => e === v).length !== b.filter(e => e === v).length)
      return false;
  return true;
haveSameContents([1, 2, 4], [2, 4, 1]); // true

Written by Angelos Chalaris

I'm Angelos Chalaris, a JavaScript software engineer, based in Athens, Greece. The best snippets from my coding adventures are published here to help others learn to code.

If you want to keep in touch, follow me on GitHub.

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