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Mapped array difference
JavaScript, Array · Oct 19, 2020
Returns the difference between two arrays, after applying the provided function to each array element of both.
- Create a
Setby applyingfnto each element inb. - Use
Array.prototype.map()to applyfnto each element ina. - Use
Array.prototype.filter()in combination withfnonato only keep values not contained inb, usingSet.prototype.has().
const differenceBy = (a, b, fn) => {
const s = new Set(b.map(fn));
return a.map(fn).filter(el => !s.has(el));
};differenceBy([2.1, 1.2], [2.3, 3.4], Math.floor); // [1]
differenceBy([{ x: 2 }, { x: 1 }], [{ x: 1 }], v => v.x); // [2]More like this
Mapped array symmetric difference
JavaScript, Array
Returns the symmetric difference between two arrays, after applying the provided function to each array element of both.
Mapped array union
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Returns every element that exists in any of the two arrays at least once, after applying the provided function to each array element of both.
Array intersection based on function
JavaScript, Array
Returns the elements that exist in both arrays, after applying the provided function to each array element of both.