Question

I was wondering how could one declare a typed-function array in TypeScript.

For instance, say I have a field which can hold a function that has no arguments and returns void:

private func: () => void;

Now, say I wanted a field which can hold an array of such functions:

private funcs: () => void  [];

This is obviously the wrong way to do what I intended since the compiler considers this to be a function which returns an array of voids.

Trying to isolate the inline prototype declaration with parentheses as in:

private funcs2: (  () => void  ) [];

causes a compiler error.

Does anyone have an idea of how this could be accomplished ?

Answer 1

You’ll need to use the full type literal syntax instead of the => shorthand:

private funcs: { (): void; }[];

You could also make an interface if that looks too weird:

// (elsewhere at top-level)
interface foo {
    (): void;
}

class etc {
    private funcs: foo[];
}