When I used kind of this["xxx"], it doesn't show the IntelliSense

export interface base {
    id: {};
}
export class a {
    b: base;
    a1<key1 extends keyof typeof this.b>(key: key1) {}
    a2<key1 extends keyof base>(key: key1) {}
    e() {
        this.a1(""); //this won't showing the intellisense 
        this.a2("id"); // this works well
    }
}

When I try to add a class and extends the base override the type b, but seems only show the key list of the base not base2

export interface base2 extends base {
    name: string;
}
export class b extends a {
    b:base2
    e(): void {
        this.a1("") // only show keyof the base not the base2
    }
}

CodePudding user response：

It may indeed be confusing that the type itself works (this.a1("id") is recognized as compliant), but not beforehand through IntelliSense.

I guess the allocated analysis resource for IntelliSense is limited, hence it may have more trouble inferring/resolving the potential type.

In your case, you can simplify the type as directly keyof typeof this.b to help IntelliSense discover more easily the available values:

export class a {
    b: base = { id: {} };

    a1<key1 extends keyof this["b"]>(key: key1) { }
    // Use a simpler type constraint
    a1b<key1 extends keyof typeof this.b>(key: key1) { }
    a2<key1 extends keyof base>(key: key1) { }

    e() {
        this.a1(""); //this won't showing the intellisense
        //   ^? a.a1<keyof this["b"]>(key: keyof this["b"]): void
        this.a1b("");
        //   ^? a.a1b<"id">(key: "id"): void // Much simpler!
        this.a2("id"); // this works well
    }
}

Playground Link