array-group-to-map.js•1.13 kB
'use strict';
var bind = require('../internals/function-bind-context');
var uncurryThis = require('../internals/function-uncurry-this');
var IndexedObject = require('../internals/indexed-object');
var toObject = require('../internals/to-object');
var lengthOfArrayLike = require('../internals/length-of-array-like');
var MapHelpers = require('../internals/map-helpers');
var Map = MapHelpers.Map;
var mapGet = MapHelpers.get;
var mapHas = MapHelpers.has;
var mapSet = MapHelpers.set;
var push = uncurryThis([].push);
// `Array.prototype.groupToMap` method
// https://github.com/tc39/proposal-array-grouping
module.exports = function groupToMap(callbackfn /* , thisArg */) {
var O = toObject(this);
var self = IndexedObject(O);
var boundFunction = bind(callbackfn, arguments.length > 1 ? arguments[1] : undefined);
var map = new Map();
var length = lengthOfArrayLike(self);
var index = 0;
var key, value;
for (;length > index; index++) {
value = self[index];
key = boundFunction(value, index, O);
if (mapHas(map, key)) push(mapGet(map, key), value);
else mapSet(map, key, [value]);
} return map;
};