@quinck/collections/lib/arrays/groupBy.js

Allows extra operations on JavaScript collections: Array, Map and Set.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
Array.prototype.groupBy = function (keyMapper, valueMapper, mergeFunction = (_, b) => b) {
    const _self = this;
    return _self.reduce((map, item) => {
        const key = keyMapper(item);
        const value = valueMapper(item);
        const prevValue = map.get(key);
        map.set(key, prevValue ? mergeFunction(prevValue, value) : value);
        return map;
    }, new Map());
};
Array.prototype.groupByToDictionary = function (keyMapper, valueMapper, mergeFunction = (_, b) => b) {
    const _self = this;
    return _self.reduce((object, item) => {
        const key = keyMapper(item);
        const value = valueMapper(item);
        const prevValue = object[key];
        object[key] = prevValue ? mergeFunction(prevValue, value) : value;
        return object;
    }, {});
};
Array.prototype.simpleGroupBy = function (keyMapper) {
    const _self = this;
    return _self.groupBy(keyMapper, v => [v], (a, b) => a.concat(b));
};
Array.prototype.simpleGroupByToDictionary = function (keyMapper) {
    const _self = this;
    return _self.groupByToDictionary(keyMapper, v => [v], (a, b) => a.concat(b));
};