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Negative constant enums return number when toString is called #54992
Description
⏯ Playground Link
💻 Code
const enum TestEnum {
A = 1,
B = -1
}
// "string", "string"
console.log(
typeof String(TestEnum.A),
typeof TestEnum.A.toString()
)
// "string", "number"
console.log(
typeof String(TestEnum.B),
typeof TestEnum.B.toString()
)🙁 Actual behavior
Constant enums which use negative numbers will return type of number when .toString() is called.
🙂 Expected behavior
A string type should be returned
Activity
[-]Negative numbered constant enums return typeof number when toString is called[/-][+]Negative numbered constant enums return number when toString is called[/+]fatcerberus commentedon Jul 12, 2023
If anyone's wondering how this happens, it's because the emit is
-1 .toString()- property access has higher precedence than negation. So effectively what happens is this logs the result oftypeof -(1..toString())-- which isnumber.[-]Negative numbered constant enums return number when toString is called[/-][+]Negative constant enums return number when toString is called[/+]RyanCavanaugh commentedon Jul 12, 2023
I'm honestly shocked this has been shipping since at least 3.3, possibly forever, without getting noticed 😰
fatcerberus commentedon Jul 12, 2023
I don’t think people generally call methods on enum values, since they’re usually just meant to be used as sentinels. Probably even fewer people still use negative values.