Argument of type 'Function' is not assignable to parameter of type '(...args: any[]) => void'. Type 'Function' provides no match for the signature '(...args: any[]): void'

typescript_function_type_error_test.ts

function on(event: string, listener: Function) {
	console.log('on event: ', event, 'typeof listener:', typeof (listener));
	listener();
}

function on1(event: string, listener: (...args: any[]) => void) {
	console.log('on event: ', event, 'typeof listener:', typeof (listener));
	listener();
}

// function createCallback(a: number): Function {
// 	let f = (a: number) => {
// 		console.log('return a:', a);
// 		return (a: number) => { return a + 1 };
// 	};
// 	return f(a);
// }

function createCallback(a: number): (a: number) => number {
	let f = (a: number) => {
		console.log('return a:', a);
		return (a: number) => { return a + 1 };
	};
	return f(a);
}

function createHellCallback(a: number) : (a: number) => ((a: number) => number) {
	let f = (a: number) => {
		console.log('return a:', a);
		return (a: number) => { 
			return (a: number) => {
				return a+1;
			}
		};
	};
	return f(a);
}

function createHellCallback1(a: number) : (a: number) => any {
	let f = (a: number) => {
		console.log('return a:', a);
		return (a: number) => { 
			return (a: number) => {
				return a+1;
			}
		};
	};
	return f(a);
}

// let f = createCallback(1);
let f = createHellCallback1(1);
console.log('type of f', typeof (f));
// on("start", f);
on1("start", f);

hi @xcaptain, I have a related to your code not the problem.

I intend to call listeners with an additional parameter, like this

  ...
  listener(new_argument, ...args);

can you help with this, I can't access listener.arguments

@radiumrasheed Hello, I think the problem you faced is not the same problem I faced. This gist is related to https://stackoverflow.com/questions/51744927/argument-of-type-function-is-not-assignable-to-parameter-of-type-args-an

For your problem, I think you mean

function on1(event: string, listener: (...args: any[]) => void) {
	console.log('on event: ', event, 'typeof listener:', typeof (listener));
	listener(1, 2);
}
function createCallback(a: number): (a: number, b: number) => number {
	let f = (a: number) => {
		return (a: number, b: number) => {
			console.log('run callback', a, b)
			return a + b + 1;
		};
	};
	return f(a);
}

If createCallback creates a closure, and it takes 2 numbers, then you can call it with listener(1, 2). If you want to create a closure that can take listener(new_argument, ...args); I think you would better define the arguments type first.