30-seconds-of-code/snippets/allUnique.md

title, tags, expertise, firstSeen, lastUpdated

title	tags	expertise	firstSeen	lastUpdated
Check if all array elements are unique	array	beginner	2020-10-19T19:47:26+03:00	2021-01-08T00:23:44+02:00

Checks if all elements in an array are unique.

• Create a new Set from the mapped values to keep only unique occurrences.
• Use Array.prototype.length and Set.prototype.size to compare the length of the unique values to the original array.

const allUnique = arr => arr.length === new Set(arr).size;

allUnique([1, 2, 3, 4]); // true
allUnique([1, 1, 2, 3]); // false