TypeScript - How to define Function Type having arguments with any Type

Question

I'm new to TypeScript.

I want to define Function Type having arguments with any Type. The function may one argument or more than two argument.

How should I write?

(args: any) => any

Writing this way above works only when one argument is passed to the function.

class NotificationCenter {

    private observerList: Array<() => any>;

    constructor() {
        this.observerList = [];
    }

    addObserver(observer: () => any): void {

        this.observerList.push(observer);

    }

}


let notificationCenter: NotificationCenter = new NotificationCenter();

let observer1 = () => {};
let observer2 = (text: string) => {return "observer2"};
let observer3 = (id: number, data: Array<any>) => {return "observer3"};

//This works fine.
notificationCenter.addObserver(observer1);

//Error:Argument of type '(text: string) => string' is not assignable to parameter of type '() => any'.
notificationCenter.addObserver(observer2);

//Error:Argument of type '(id: number, data: any[]) => string' is not assignable to parameter of type '() => any'.
notificationCenter.addObserver(observer3);

I think what you want is (...params : any[]) => any. See this — tforgione
– tforgione, Commented Mar 31, 2016 at 15:00
@tforgione I think this is a good answer. If you submit it as an answer I'll upvote it. — Matthew Nichols
– Matthew Nichols, Commented Mar 7, 2023 at 23:40

rgvassar · Accepted Answer · 2016-03-31 15:13:27Z

1

You say the function can have one argument or more than two arguments. That sounds like it can have one or 3 or more arguments. You'll have to overload it then.

function foo(arg: any): any { /*do work*/ }
function foo(arg: any, arg2: any, ...rest: any[]): any { /*do work*/ }

answered Mar 31, 2016 at 15:13

rgvassar

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