create an object based on the type of another object in TypeScript

Question

how to create an object based on the type of another object in TypeScript

obj1 = new Object();

obj2 = new "obj1.constructor.name"

I have to do like that because Object 1 can have different class .

new obj1.constructor() should work. BTW this has nothing to do with TypeScript. — user663031
– user663031, Commented Aug 12, 2016 at 8:56
when I use obj1.constructor i ahve this error ""Cannot use 'new' with an expression whose type lacks a call or construct signature."" — imtah
– imtah, Commented Aug 12, 2016 at 9:10
Could you please add more information? It is not clear what you really want. Do you want to inherit/extend from another class? — Sebastian Sebald
– Sebastian Sebald, Commented Aug 12, 2016 at 9:42

Nitzan Tomer · Accepted Answer · 2016-08-12 10:00:26Z

2

The typescript compiler will complain if you try to do:

new obj1.constructor()

But you can tell it that it's ok like this:

class A {}

class B extends A {}

type AConstructor = {
    new(): A;
}

type BConstructor = {
    new(): B;
}

let a1 = new A();
let a2 = new (a1.constructor as AConstructor)();

let b1 = new B();
let b2 = new (b1.constructor as BConstructor)();

(code in playground)

answered Aug 12, 2016 at 10:00

Nitzan Tomer

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