Check if arrays have same contents

Angelos Chalaris · 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

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