how to make data2 and data3 work and data1 error with type like in the following code?

I want to make sure that if the user just enters params {name: 'aa', age: 20} it is an error, because parameters need to include data type date(key name can be anything) like {name: 'aa', age: 20, born: new Date('10-10-2020')

const data1 = {
  name: 'Lorem',
  age: 12
}

const data2 = {
  name: 'Lorem',
  age: 12,
  born: new Date('10/10/1990')
}

const data3 = {
  name: 'epsum',
  age: 12,
  died: new Date('10/10/1990')
}

interface PropsA {
  name: string;
  age: number;
}

const test = (inputParams: PropsA & { [x: string]: Date }) => {
  return inputParams
}

test(data1) //it should be an error because it doesn't have a value with data type Date other than age and name

//how to make this work and not error?
test(data2) 
test(data3)

Playground

CodePudding user response：

Possible with a generic utility type to validate the given type:

type HasDate<T> = Date extends T[keyof T] ? T : never;

const test = <T extends PropsA>(inputParams: HasDate<T>) => {
  return inputParams;
};

TS will be smart enough to infer T through HasDate.

test(data1) // ! errors
test(data2) // ok
test(data3) // ok

Playground

Your attempt doesn't work since { [x: string]: Date } means all keys must have Date values. That obviously isn't the case for PropA, so data2 and data3 fail.