Repository navigation
Enum lookup for map type [P in Enum] gives "implicit any index" error #19546
Description
TypeScript Version: 2.5.3
It could be I stumbled on something I simply don't understand, but it seems like this should work:
Code
enum Color {
RED = "RED",
BLUE = "BLUE",
GREEN = "GREEN"
}
type ColorMap = {
[P in Color]: number; // type ColorMap = { RED: number; BLUE: number; GREEN: number; }
}
declare const color: Color;
map[color] // Error: Element implicitly has an 'any' type because type 'ColorMap' has no index signature.All of the following work:
declare const map: ColorMap;
map[Color.RED] // OK
const red: Color = Color.RED;
map[red] // OK
declare const color: keyof typeof Color;
map[color] // OK -- I don't know why this worksExpected behavior:
map[color] to work and give return type of number
Actual behavior:
map[color] // Error: Element implicitly has an 'any' type because type 'ColorMap' has no index
Activity
aaronbeall commentedon Oct 28, 2017
More stuff I don't understand:
aaronbeall commentedon Oct 28, 2017
I think my confusion lies with how the compiler actually "sees" the
enumtype... I thought that string enum was equivalent to the old string literaltype+namespaceworkaround:But it obviously is a different thing that isn't as intuitive to me...
aluanhaddad commentedon Oct 28, 2017
I've also found this very counterintuitive. The workaround was more verbose but was expressive and allowed for very convenient consumption.
[-]Enum lookip[/-][+]Enum lookup for map type [P in Enum] gives "implicit any index" error[/+]mhegazy commentedon Oct 30, 2017
Duplicate of #16760. Should be fixed by #18029
typescript-bot commentedon Nov 13, 2017
Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.