Here is a snippet of code I'm working with in the TypeScript playground:
interface IFoo {
new?(): string;
}
class Foo implements IFoo {
new() {
return 'sss';
}
}
I noticed that I have to include "?" in the interface method "new" to avoid a compile error, but I'm not sure why.
Update: The original question may not be the best approach for using "new," so I've provided a more practical example below:
interface IUser {
id: number;
name: string;
}
interface UserConstructable {
new (id: number, name: string, ...keys: any[]): IUser;
}
class User implements IUser {
constructor(public id: number, public name: string) {
}
}
class Employee implements IUser {
constructor(public id: number, public name: string, private manager: string) {
}
}
class UserFactory {
private static _idx: number = 0;
static makeUser(n: UserConstructable): IUser {
let newId = UserFactory._idx++;
return new n(newId, 'user-' + newId, 'manager-' + newId);
}
}
console.log(UserFactory.makeUser(User));
console.log(UserFactory.makeUser(User));
console.log(UserFactory.makeUser(Employee));