1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
|
// Copyright (C) 2016 the V8 project authors. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
es6id: 14.1.6
description: >
Default parameters' effect on function length
info: |
Function length is counted by the non initialized parameters in the left.
9.2.4 FunctionInitialize (F, kind, ParameterList, Body, Scope)
[...]
2. Let len be the ExpectedArgumentCount of ParameterList.
3. Perform ! DefinePropertyOrThrow(F, "length", PropertyDescriptor{[[Value]]:
len, [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true}).
[...]
FormalsList : FormalParameter
1. If HasInitializer of FormalParameter is true return 0
2. Return 1.
FormalsList : FormalsList , FormalParameter
1. Let count be the ExpectedArgumentCount of FormalsList.
2. If HasInitializer of FormalsList is true or HasInitializer of
FormalParameter is true, return count.
3. Return count+1.
features: [default-parameters]
includes: [propertyHelper.js]
---*/
function f1(x = 42) {}
assert.sameValue(f1.length, 0, 'FormalsList: x = 42');
verifyNotEnumerable(f1, 'length');
verifyNotWritable(f1, 'length');
verifyConfigurable(f1, 'length');
function f2(x = 42, y) {}
assert.sameValue(f2.length, 0, 'FormalsList: x = 42, y');
verifyNotEnumerable(f2, 'length');
verifyNotWritable(f2, 'length');
verifyConfigurable(f2, 'length');
function f3(x, y = 42) {}
assert.sameValue(f3.length, 1, 'FormalsList: x, y = 42');
verifyNotEnumerable(f3, 'length');
verifyNotWritable(f3, 'length');
verifyConfigurable(f3, 'length');
function f4(x, y = 42, z) {}
assert.sameValue(f4.length, 1, 'FormalsList: x, y = 42, z');
verifyNotEnumerable(f4, 'length');
verifyNotWritable(f4, 'length');
verifyConfigurable(f4, 'length');
reportCompare(0, 0);
|
