Conditional type property on generic class

Question

why does this not work??

export class Client<isReady extends boolean = false> {
  user: isReady extends true ? ClientUser : null = null
}

Deno throws this error Type 'null' is not assignable to type 'isReady extends true ? ClientUser : null'.deno-ts(2322) on the user property

I want the user property to be only of type null at some places and only of type ClientUser at some places and I also want it to be initialized with the value as null.

Answer 1

You could use the ! operator as suffix of user:

export class Client {
  user!: ClientUser
}

But I do not recommend this because you will lose typescript checks.

It is better to use ClientUser | null union, you need the do some null check, but you will keep your code type safe.