mary.my.id
small array utilities
feat: differenceBy function
author
Mary
date
(Feb 2, 2025, 11:39 AM +0700)
commit
c80cd746
c80cd7461ba75e06a383184e043536bbf1c09314
parent
85109256
851092567e0675779f1fabf8aa2f076aa8eab022
+24
+24
lib/mod.ts
+24
lib/mod.ts
···
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};
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/**
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* returns elements present in the first array but not in the second, based on a selector
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* @param a the source array
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* @param b the array to compare against
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* @param selector function to derive comparison keys
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* @returns an array of elements in a not present in b based on the selector
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*/
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/*#__NO_SIDE_EFFECTS__*/
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export const differenceBy = <T, K>(a: T[], b: T[], selector: (value: T) => K): T[] => {
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const bSet = new Set(b.map(selector));
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const aSet = new Set<K>();
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return a.filter((value) => {
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const key = selector(value);
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if (!bSet.has(key) && !aSet.has(key)) {
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aSet.add(key);
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return true;
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}
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return false;
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});
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};
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/**
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* returns elements common to both arrays
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* @param a the first array
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* @param b the second array