I have a generic function that looks like this:
private getItem<T>(identifier: string): T {...}
Now I want to change this, so that the return type can be any object or array, but not any and also not string. I'm unsure how to achieve that.
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1Take a look at Generic Constraintsthedude– thedude2023-02-08 13:04:29 +00:00Commented Feb 8, 2023 at 13:04
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2 Answers
If you want to disallow the use of any, you'll need a little more magic. Using a type from this question to check for any, we can then use something like
type IfAny<T, Y, N> = 0 extends (1 & T) ? Y : N;
declare function foo<T extends IfAny<T, never, object>>(): T;
If T is any, then the constraint is never, otherwise, the constraint is object.
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aaaaaa
the current playground shows "Type parameter 'T' has a circular constraint". Probably an update in ts since this was written
T extends object can be use for objects and arrays, but not primitives and any:
private getItem<T extends object>(identifier: string): T {...}
2 Comments
k.tten
This does not protect against
any: tsplay.dev/Wvq8Qm
protob
you got that right