Reuse a function type's argument definition-CodePudding

In typescript is there a way to reuse parameter types as follows:

interface Box {
    create: (paramToReuse: (value: any) => void) => void
}
// is there a way to reference paramToResuse as a type? e.g.
let x: Box['create']['paramToReuse']

This can be done the other way around: by first defining paramToReuse and then referencing it in Box's interface, but can it be done the way I've shown above?

CodePudding user response：

If it's acceptable to reference it by its parameter index (0) instead of its name ("paramToUse"), that can be done with the helper type Parameters, which takes a function and turns it into a tuple of its parameters:

interface Box {
    create: (paramToReuse: (value: any) => void) => void
}

let x: Parameters<Box["create"]>[0] // x is of type (value: any) => void

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