ArraySpeciesCreate.js

'use strict';

var GetIntrinsic = require('get-intrinsic');

var $Array = GetIntrinsic('%Array%');
var $species = GetIntrinsic('%Symbol.species%', true);
var $TypeError = GetIntrinsic('%TypeError%');

var Get = require('./Get');
var IsArray = require('./IsArray');
var IsConstructor = require('./IsConstructor');
var IsInteger = require('./IsInteger');
var Type = require('./Type');

// https://ecma-international.org/ecma-262/6.0/#sec-arrayspeciescreate

module.exports = function ArraySpeciesCreate(originalArray, length) {
	if (!IsInteger(length) || length < 0) {
		throw new $TypeError('Assertion failed: length must be an integer >= 0');
	}
	var len = length === 0 ? 0 : length;
	var C;
	var isArray = IsArray(originalArray);
	if (isArray) {
		C = Get(originalArray, 'constructor');
		// TODO: figure out how to make a cross-realm normal Array, a same-realm Array
		// if (IsConstructor(C)) {
		// 	if C is another realm's Array, C = undefined
		// 	Object.getPrototypeOf(Object.getPrototypeOf(Object.getPrototypeOf(Array))) === null ?
		// }
		if ($species && Type(C) === 'Object') {
			C = Get(C, $species);
			if (C === null) {
				C = void 0;
			}
		}
	}
	if (typeof C === 'undefined') {
		return $Array(len);
	}
	if (!IsConstructor(C)) {
		throw new $TypeError('C must be a constructor');
	}
	return new C(len); // Construct(C, len);
};