File size: 615 Bytes
4e1096a | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | // A groupBy polyfill for foliate-js
Object.groupBy ??= (iterable, callbackfn) => {
const obj = Object.create(null);
let i = 0;
for (const value of iterable) {
const key = callbackfn(value, i++);
if (key in obj) {
obj[key].push(value);
} else {
obj[key] = [value];
}
}
return obj;
};
Map.groupBy ??= (iterable, callbackfn) => {
const map = new Map();
let i = 0;
for (const value of iterable) {
const key = callbackfn(value, i++),
list = map.get(key);
if (list) {
list.push(value);
} else {
map.set(key, [value]);
}
}
return map;
};
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