forked from akai/readest
Huang Xin
30 lines
615 B
TypeScript
30 lines
615 B
TypeScript
// A groupBy polyfill for foliate-js
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Object.groupBy ??= (iterable, callbackfn) => {
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const obj = Object.create(null);
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let i = 0;
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for (const value of iterable) {
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const key = callbackfn(value, i++);
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if (key in obj) {
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obj[key].push(value);
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} else {
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obj[key] = [value];
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}
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}
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return obj;
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};
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Map.groupBy ??= (iterable, callbackfn) => {
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const map = new Map();
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let i = 0;
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for (const value of iterable) {
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const key = callbackfn(value, i++),
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list = map.get(key);
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if (list) {
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list.push(value);
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} else {
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map.set(key, [value]);
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}
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}
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return map;
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};
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