How do I type an array of CallableFunction's that might be async?

Issue

I have this code:

export const provide = async (callables: CallableFunction[]) => {
    for (const callable of callables) {
        await callable()
    }
}

A callable may or may not be async.

I've tried typing it like this:

export const provide = async (callables: CallableFunction[] | Promise<CallableFunction>[]) => {
    for (const callable of callables) {
        await callable()
    }
}

But vscode gives me the error:

This expression is not callable. No constituent of type 'CallableFunction | Promise' is callable.

How do I type an array of CallableFunction's that may or may not be async?

Solution

CallableFunction includes any would-be async functions -

const provide = async (callables: CallableFunction[]) => {
    for (const callable of callables) {
        await callable()
    }
}

provide([
    () => { console.log("hello") },
    async () => { 
        await new Promise(r => setTimeout(r, 1000))
        console.log("world")
    },
])

hello
world

typescript playground

---

According to your comment, it sounds like the CallableFunction interface is not suitable for your needs -

const provide = async (callables: Array<() => void | Promise<void>>) => {
    for (const callable of callables) {
        await callable()
    }
}

Now you can see a more explicit type -

Answered By - Mulan