@extra-array/is-unique-on

Checks if there are no duplicate values. 🏃 📼 📦 🌔

Alternatives: compare, map.
This is part of package extra-array.

array.isUniqueOn(x, [fn], [ths]);
// x:   an array
// fn:  map function (v, i, x)
// ths: this argument

const array = require('extra-array');

var x = [1, 2, -1, -2];
array.isUniqueOn(x);
// true

array.isUniqueOn(x, v => Math.abs(v));
// false

Readme