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
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
|
// Section numbers cite ES6 rev 24 (2014 April 27).
var symbols = [
Symbol(),
Symbol("one"),
Symbol.for("two"),
Symbol.iterator
];
function testSymbolConversions(sym) {
// 7.1.2 ToBoolean
assertEq(Boolean(sym), true);
assertEq(!sym, false);
assertEq(sym || 13, sym);
assertEq(sym && 13, 13);
// 7.1.3 ToNumber
assertThrowsInstanceOf(() => +sym, TypeError);
assertThrowsInstanceOf(() => sym | 0, TypeError);
// 7.1.12 ToString
assertThrowsInstanceOf(() => "" + sym, TypeError);
assertThrowsInstanceOf(() => sym + "", TypeError);
assertThrowsInstanceOf(() => "" + [1, 2, sym], TypeError);
assertThrowsInstanceOf(() => ["simple", "thimble", sym].join(), TypeError);
// 21.1.1.1 String()
assertEq(String(sym), sym.toString());
// 21.1.1.2 new String()
assertThrowsInstanceOf(() => new String(sym), TypeError);
// 7.1.13 ToObject
var obj = Object(sym);
assertEq(typeof obj, "object");
assertEq(Object.prototype.toString.call(obj), "[object Symbol]");
assertEq(Object.getPrototypeOf(obj), Symbol.prototype);
assertEq(Object.getOwnPropertyNames(obj).length, 0);
assertEq(Object(sym) === Object(sym), false); // new object each time
var f = function () { return this; };
assertEq(f.call(sym) === f.call(sym), false); // new object each time
}
for (var sym of symbols) {
testSymbolConversions(sym);
// 7.1.1 ToPrimitive
var symobj = Object(sym);
assertThrowsInstanceOf(() => Number(symobj), TypeError);
assertThrowsInstanceOf(() => String(symobj), TypeError);
assertThrowsInstanceOf(() => symobj < 0, TypeError);
assertThrowsInstanceOf(() => 0 < symobj, TypeError);
assertThrowsInstanceOf(() => symobj + 1, TypeError);
assertThrowsInstanceOf(() => "" + symobj, TypeError);
assertEq(sym == symobj, true);
assertEq(sym === symobj, false);
assertEq(symobj == 0, false);
assertEq(0 != symobj, true);
// 7.1.12 ToString
assertThrowsInstanceOf(() => String(Object(sym)), TypeError);
}
// Deleting Symbol.prototype[@@toPrimitive] does not change the behavior of
// conversions from a symbol to other types.
delete Symbol.prototype[Symbol.toPrimitive];
assertEq(Symbol.toPrimitive in Symbol.prototype, false);
testSymbolConversions(symbols[0]);
// It does change the behavior of ToPrimitive on Symbol objects, though.
// It causes the default algorithm (OrdinaryToPrimitive) to be used.
var VALUEOF_CALLED = 117.25;
Symbol.prototype.valueOf = function () { return VALUEOF_CALLED; };
Symbol.prototype.toString = function () { return "toString called"; };
for (var sym of symbols) {
var symobj = Object(sym);
assertEq(Number(symobj), VALUEOF_CALLED);
assertEq(String(symobj), "toString called");
assertEq(symobj < 0, VALUEOF_CALLED < 0);
assertEq(0 < symobj, 0 < VALUEOF_CALLED);
assertEq(symobj + 1, VALUEOF_CALLED + 1);
assertEq("" + symobj, "" + VALUEOF_CALLED);
assertEq(symobj == 0, false);
assertEq(0 != symobj, true);
}
if (typeof reportCompare === "function")
reportCompare(0, 0);
|
