How to write an interface with base value and unknown amount of dynamic properties?-CodePudding

I have an object structure which could be as follows:

const myObj = {
  callback : ( val : boolean ) => concole.log( val ),
  string1  : 'foo',
  string2  : 'bar',
  string3  : 'bla',
  // eventually string4, string5 etc.
}

Is there a way to define an interface where the object has an optional property callback and optional properties string num?

Like:

interface MyInterface {
  callback                                ?: ( val ?: boolean ) => void;
  [ ( must be "string"   num ) : string ] ?: string
}

So the only allowed props would be callback followed by string1, string2 and so forth wit no limit like string200.

Is this possible?

CodePudding user response：

We can now use template literal types as keys in index signatures:

interface MyInterface {
    callback?: (val?: boolean) => void;
    [key: `string${bigint}`]: string;
}

I've used bigint instead of number so only integers are allowed.

This allows keys like string1 and string123 but not string or string1.2 (or the cases @jcalz showed