debian-mirror-gitlab/core-js/modules/esnext.map.reduce.js
2019-10-31 01:37:42 +05:30

29 lines
1.1 KiB
JavaScript

'use strict';
var $ = require('../internals/export');
var IS_PURE = require('../internals/is-pure');
var anObject = require('../internals/an-object');
var aFunction = require('../internals/a-function');
var getMapIterator = require('../internals/get-map-iterator');
var iterate = require('../internals/iterate');
// `Map.prototype.reduce` method
// https://github.com/tc39/proposal-collection-methods
$({ target: 'Map', proto: true, real: true, forced: IS_PURE }, {
reduce: function reduce(callbackfn /* , initialValue */) {
var map = anObject(this);
var iterator = getMapIterator(map);
var noInitial = arguments.length < 2;
var accumulator = noInitial ? undefined : arguments[1];
aFunction(callbackfn);
iterate(iterator, function (key, value) {
if (noInitial) {
noInitial = false;
accumulator = value;
} else {
accumulator = callbackfn(accumulator, value, key, map);
}
}, undefined, true, true);
if (noInitial) throw TypeError('Reduce of empty map with no initial value');
return accumulator;
}
});