[Question] Other object's properties eq to {[key:string]: string} in TypeScript

[moshfeu]

I wanted to ask what is the equivalent way (if there is one) to declare a type with specific required property and unlimited optional properties as the following typescript code:

interface BaseEntity {
  id: string;
}

interface Entity extends BaseEntity {
  [key: string]: string;
}

For example:

{ id: 'some_id' } // valid
{ id: 'some_id', foo: 'bar' } // valid
{ } // invalid
{ foo: 'bar' } // invalid

Example of how it works in TypeScript

https://www.typescriptlang.org/play/#code/JYOwLgpgTgZghgYwgAgEJwM4QKLmGAT2QG8AoZZYAEwC5kMwpQBzAblIF9TTRJZEUuMPiIQAHpBBUMaTDjyES5ZAG0A1hAJ0GTEMwC62xi3ZdSCAPYgGyOHSEjkAXiUVqdAOQAjADZwPADTKMBYWnl5wUB6c3JbWYMhe9gpELmQUIWHI3pHRHEA

I use it for TypeScript "Type Checking JavaScript Files" and I hope that the solution is also fit in this case.

Thanks!