What is the proper way to indicate that a function parameter corresponds to one of an Interface's keys?

Question

What is the proper way to indicate that a function parameter corresponds to one of an Interface's keys?

When working with TypeScript, I am looking for a way to validate that the argument passed to myFunction matches one of the keys defined in MyInterface. Essentially, I want to enforce type checking on the arg parameter as shown below.

export interface MyInterface {
  option1: boolean;
  option2: boolean;
  option3: boolean;
  option4: boolean;
}


myFunction(arg: 'option1' | 'option2' | 'option3' | 'option4'): void {
    console.log("arg:", option)
}

I understand that I can use let myVar : keyof typeof obj to specify a variable as one of the keys of an Object, as explained here. Is there a similar approach for Interfaces? Is it possible to achieve the desired behavior without explicitly listing 'option1' | 'option2' | ...? In other words, is there a way to declare arg: in MyInterface.keys?

typescript

Answer 1

Answer №1

Absolutely, the keyof type operator can definitely be utilized.

You have the option to implement it like this: 

function myFunction(arg: keyof MyInterface): void {
  console.log("arg:", arg);
}

Interested in seeing it in action? Check out this Playground link to code

Answer 2

Absolutely, the keyof type operator can definitely be utilized.

You have the option to implement it like this: 

function myFunction(arg: keyof MyInterface): void {
  console.log("arg:", arg);
}

Interested in seeing it in action? Check out this Playground link to code

What is the proper way to indicate that a function parameter corresponds to one of an Interface's keys?

Answer №1

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