A Typed array of functions

I'm struggling to figure out if it's possible in TypeScript to declare a statically typed array of functions.

For example, I can do this:

foo: (data:string) => void = function (data) {};

But if I want foo to be an array of functions that take a string and return nothing, how do I do that?

foo: (data:string) => void [] = [];

Doesn't work because TypeScript thinks it's a function that takes a string and returns an array of void, and it doesn't seem to like me trying to wrap the function in brackets.

Any ideas?

Answer: Thanks to mohamed below, here's an example that works in the TypeScript Playground:

class whatever {
public foo: { (data: string): void; }[] = [];

    dofoo() {
        for (var i=0; i < this.foo.length; i++) {
             this.foo[i]("test");
        }
    }
}

var d = new whatever();

d.foo.push(function(bar){alert(bar)})
d.foo.push(function(bar){alert(bar.length.toString())})

d.dofoo();

You can find this in the language spec section 3.6.4:

foo: { (data: string): void; } []

Other (newer, more readable) ways to type an array of functions using fat arrows:

let foo: Array<(data: string) => void>;
let bar: ((data: string) => void)[];

or foo: ((data: string) => void)[]

If you wish declare an array of callable function in TypeScript, you can declare a type:

type Bar = (
  (data: string) => void
);

And then use it:

const foo: Bar[] = [];

const fooFn = (data: string) => console.log(data);
foo.push(fooFn);
foo.forEach((fooFn: Bar) => fooFn("Something");

A Typed array of functions

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