8ee50178f3
Correct: `Array.from()` (it’s a static method) Incorrect: `Array.join()` (doesn’t exist; it’s a prototype method) This patch uses the common `#` syntax to denote `.prototype.`.
610 B
610 B
symmetricDifferenceBy
Returns the symmetric difference between two arrays, after applying the provided function to each array element of both.
Create a Set by applying fn to each array's elements, then use Array.prototype.filter() on each of them to only keep values not contained in the other.
const symmetricDifferenceBy = (a, b, fn) => {
const sA = new Set(a.map(v => fn(v))),
sB = new Set(b.map(v => fn(v)));
return [...a.filter(x => !sB.has(fn(x))), ...b.filter(x => !sA.has(fn(x)))];
};
symmetricDifferenceBy([2.1, 1.2], [2.3, 3.4], Math.floor); // [ 1.2, 3.4 ]