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// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Flags: --harmony-array-flatten --allow-natives-syntax
assertEquals(Array.prototype.flatMap.length, 1);
assertEquals(Array.prototype.flatMap.name, 'flatMap');
assertEquals(
[1, 2, 3, 4].flatMap((element) => [element, element ** 2]),
[1, 1, 2, 4, 3, 9, 4, 16]
);
assertEquals(
[1, 2, 3, 4].flatMap((element) => [[element, element ** 2]]),
[[1, 1], [2, 4], [3, 9], [4, 16]]
);
const elements = new Set([
-Infinity,
-1,
-0,
+0,
+1,
Infinity,
null,
undefined,
true,
false,
'',
'foo',
/./,
[],
{},
Object.create(null),
new Proxy({}, {}),
Symbol(),
x => x ** 2,
String
]);
for (const value of elements) {
assertEquals(
[value].flatMap((element) => [element, element]),
[value, value]
);
}
const array = [42];
assertEquals(
[array].flatMap((element) => [element, element]),
[array, array]
);
const nonCallables = new Set([
-Infinity,
-1,
-0,
+0,
+1,
Infinity,
null,
undefined,
true,
false,
'',
'foo',
/./,
[],
{},
Object.create(null),
new Proxy({}, {}),
Symbol(),
]);
for (const nonCallable of nonCallables) {
assertThrows(() => {
[].flatMap(nonCallable);
}, TypeError);
}
const object = {
foo: 42,
get length() {
object.foo = 0;
}
};
const result = [object].flatMap((element) => [element, element]);
%HeapObjectVerify(result);
assertEquals(result, [object, object]);
assertEquals(result[0].foo, 42);
assertThrows(() => {
Array.prototype.flatMap.call(null, (element) => element);
}, TypeError);
assertThrows(() => {
Array.prototype.flatMap.call(undefined, (element) => element);
}, TypeError);
assertEquals(
Array.prototype.flatMap.call(
{
length: 1,
0: 'a',
1: 'b',
},
(element) => element
),
['a']
);
assertEquals(
Array.prototype.flatMap.call(
{
length: 2,
0: 'a',
1: 'b',
},
(element) => element
),
['a', 'b']
);
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