como usar o symmetricDifferenceBy no javascript es6

January 04, 2020

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 ]

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