15 lines
360 B
JavaScript
15 lines
360 B
JavaScript
'use strict';
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Object.defineProperty(exports, Symbol.toStringTag, { value: 'Module' });
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function countBy(map, mapper) {
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const result = new Map();
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for (const [key, value] of map) {
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const mappedKey = mapper(value, key, map);
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result.set(mappedKey, (result.get(mappedKey) ?? 0) + 1);
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}
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return result;
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}
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exports.countBy = countBy;
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