return a type by pass this type‘s name

type_query.ts

export type Name = { name: string }
export type Id = { id: number }

type Get<T extends string> =
    T extends "Name" ? Name :
    T extends "Id" ? Id :
    never


function get<T extends string>(x: T): Get<T>;
function get(x: string) {
    if (x === "Name")
        return { name: "Homura" };
    else
        return { id: 42 };
}

get("Name").name.charAt(1);
get("Id").id.toExponential(1);

type_query_2.ts

export type Name = { name: string, tag: "Name"  }
export type Id = { id: string, tag: "Id" }

type Sum = Name | Id;

type Filter<T, U> = T extends U ? T : never;
type FilterTag<T, U extends string> = Filter<T, {tag: U}>;


function get<T extends string>(x: T): FilterTag<Sum, T>;
function get(x: string) {
    if (x === "Name")
        return { name: "Homura", tag: x };
    else
        return { id: "42", tag: x };
}

get("Name").name.charAt(1);
get("Id").id.concat('');

type_query_3.ts

// https://stackoverflow.com/questions/45933462/string-literal-argument-as-compile-time-type-name


declare namespace Sum {
    export class Name {
        name: string;
    }

    export class Age {
        age: number;
    }
}


function get<K extends keyof typeof Sum>(key: K): (typeof Sum)[K]['prototype'] {
    if (key === "Name")
        return new Sum.Name();
    else
        return new Sum.Age();
}

get('Name').name.concat('a');