CODEWITHSUNDEEP
javascripttypescript
Jon Tan
Jon Tan

Reputation: 1551

Passing function as parameter in Typescript: Expected 0 arguments, but got 1.ts

I am trying to pass in this doSomething function into performAction, but the error I'm getting is Expected 0 arguments, but got 1

type someType = {
  name: string,
  id: string
}

function doSomethingFn(props: someType) {
  console.log(props.name + " " + props.id);
}

function performAction(doSomething: () => void) {
  doSomething({
    name: "foo",
    id: "bar"
  });
}

performAction(doSomethingFn);

Am I using the proper syntax for Typescript?

Upvotes: 19

Views: 28453

Answers (3)

Frank
Frank

Reputation: 1

let a = 6;
let b = 2;

let res = outer(substr, a, b);
console.log(res);
res = outer(addit, a, b);
console.log(res);

function outer(inner: Function, a: number, b: number): number {
    return inner(a,b);
}

function substr(vala: number, valb: number): number {
    console.log('We are substracting');
    return vala - valb;
}

function addit(vala: number, valb: number): number {
    console.log('We are adding');
    return vala + valb;
}

Upvotes: 0

Devansh J
Devansh J

Reputation: 4194

The doSomething type seems incorrect. In the type declaration – () => void it takes no arguments, but later you are passing arguments to it.

For this piece of code following would work, but you would know better what should be the arguments and their types of doSomething. Probably use a interface if you already have an abstraction in your mind.

function performAction(doSomething: (stuff: { name: string, id: string }) => void) {
  doSomething({
    name: "foo",
    id: "bar"
  });
}

Demo for above.

Also if string in your code is a variable you need to change that because string is reserved for the type. In case you don't what to fix the type of doSomething right now you can use the Function type. Demo


Update

For your updated question you need to write function performAction(doSomething: (stuff: someType) => void Demo

Upvotes: 20

mbojko
mbojko

Reputation: 14669

You type doSomething as a function with no arguments: doSomething: () => void. Make it, dunno, doSomething: (arg: SomeInterface) => void (SomeInterface being, for example, {name: string; id: string;}).

Upvotes: 4

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