mirror of https://github.com/tc39/test262.git
40 lines
1.3 KiB
JavaScript
40 lines
1.3 KiB
JavaScript
// Copyright (c) 2021 Rick Waldron. All rights reserved.
|
||
// This code is governed by the license found in the LICENSE file.
|
||
|
||
/*---
|
||
esid: sec-array.from
|
||
description: >
|
||
Creates an array with length that is equal to the value of the
|
||
length property of the given array-like, regardless of
|
||
the presence of corresponding indices and values.
|
||
info: |
|
||
Array.from ( items [ , mapfn [ , thisArg ] ] )
|
||
|
||
7. Let arrayLike be ! ToObject(items).
|
||
8. Let len be ? LengthOfArrayLike(arrayLike).
|
||
9. If IsConstructor(C) is true, then
|
||
a. Let A be ? Construct(C, « 𝔽(len) »).
|
||
10. Else,
|
||
a. Let A be ? ArrayCreate(len).
|
||
|
||
includes: [compareArray.js]
|
||
---*/
|
||
|
||
const length = 5;
|
||
|
||
const newlyCreatedArray = Array.from({ length });
|
||
assert.sameValue(
|
||
newlyCreatedArray.length,
|
||
length,
|
||
"The newly created array's length is equal to the value of the length property for the provided array like object"
|
||
);
|
||
assert.compareArray(newlyCreatedArray, [undefined, undefined, undefined, undefined, undefined]);
|
||
|
||
const newlyCreatedAndMappedArray = Array.from({ length }).map(x => 1);
|
||
assert.sameValue(
|
||
newlyCreatedAndMappedArray.length,
|
||
length,
|
||
"The newly created and mapped array's length is equal to the value of the length property for the provided array like object"
|
||
);
|
||
assert.compareArray(newlyCreatedAndMappedArray, [1, 1, 1, 1, 1]);
|