package.2019.CreateListFromArrayLike.js Maven / Gradle / Ivy

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ECMAScript spec abstract operations.

There is a newer version: 1.22.3

'use strict';

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

var callBound = require('call-bind/callBound');

var $TypeError = GetIntrinsic('%TypeError%');
var $indexOf = callBound('Array.prototype.indexOf', true) || callBound('String.prototype.indexOf');
var $push = callBound('Array.prototype.push');

var Get = require('./Get');
var IsArray = require('./IsArray');
var ToLength = require('./ToLength');
var ToString = require('./ToString');
var Type = require('./Type');

var defaultElementTypes = ['Undefined', 'Null', 'Boolean', 'String', 'Symbol', 'Number', 'Object'];

// https://262.ecma-international.org/6.0/#sec-createlistfromarraylike
module.exports = function CreateListFromArrayLike(obj) {
	var elementTypes = arguments.length > 1
		? arguments[1]
		: defaultElementTypes;

	if (Type(obj) !== 'Object') {
		throw new $TypeError('Assertion failed: `obj` must be an Object');
	}
	if (!IsArray(elementTypes)) {
		throw new $TypeError('Assertion failed: `elementTypes`, if provided, must be an array');
	}
	var len = ToLength(Get(obj, 'length'));
	var list = [];
	var index = 0;
	while (index < len) {
		var indexName = ToString(index);
		var next = Get(obj, indexName);
		var nextType = Type(next);
		if ($indexOf(elementTypes, nextType) < 0) {
			throw new $TypeError('item type ' + nextType + ' is not a valid elementType');
		}
		$push(list, next);
		index += 1;
	}
	return list;
};