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node_modules/es-abstract/2017/ArrayCreate.js
| 53 lines
| 1.6 KiB
| application/javascript
| JavascriptLexer
|
r789 | 'use strict'; | |||
var GetIntrinsic = require('../GetIntrinsic'); | ||||
var $ArrayPrototype = GetIntrinsic('%Array.prototype%'); | ||||
var $RangeError = GetIntrinsic('%RangeError%'); | ||||
var $SyntaxError = GetIntrinsic('%SyntaxError%'); | ||||
var $TypeError = GetIntrinsic('%TypeError%'); | ||||
var IsInteger = require('./IsInteger'); | ||||
var MAX_ARRAY_LENGTH = Math.pow(2, 32) - 1; | ||||
var $setProto = GetIntrinsic('%Object.setPrototypeOf%', true) || ( | ||||
// eslint-disable-next-line no-proto, no-negated-condition | ||||
[].__proto__ !== $ArrayPrototype | ||||
? null | ||||
: function (O, proto) { | ||||
O.__proto__ = proto; // eslint-disable-line no-proto, no-param-reassign | ||||
return O; | ||||
} | ||||
); | ||||
// https://www.ecma-international.org/ecma-262/6.0/#sec-arraycreate | ||||
module.exports = function ArrayCreate(length) { | ||||
if (!IsInteger(length) || length < 0) { | ||||
throw new $TypeError('Assertion failed: `length` must be an integer Number >= 0'); | ||||
} | ||||
if (length > MAX_ARRAY_LENGTH) { | ||||
throw new $RangeError('length is greater than (2**32 - 1)'); | ||||
} | ||||
var proto = arguments.length > 1 ? arguments[1] : $ArrayPrototype; | ||||
var A = []; // steps 5 - 7, and 9 | ||||
if (proto !== $ArrayPrototype) { // step 8 | ||||
if (!$setProto) { | ||||
throw new $SyntaxError('ArrayCreate: a `proto` argument that is not `Array.prototype` is not supported in an environment that does not support setting the [[Prototype]]'); | ||||
} | ||||
$setProto(A, proto); | ||||
} | ||||
if (length !== 0) { // bypasses the need for step 2 | ||||
A.length = length; | ||||
} | ||||
/* step 10, the above as a shortcut for the below | ||||
OrdinaryDefineOwnProperty(A, 'length', { | ||||
'[[Configurable]]': false, | ||||
'[[Enumerable]]': false, | ||||
'[[Value]]': length, | ||||
'[[Writable]]': true | ||||
}); | ||||
*/ | ||||
return A; | ||||
}; | ||||