How to get a class from a string in TypeScript/JavaScript in an Angular 2 application?

Question

In my application, I have something like this:

user.ts

export class User { ... }

and right now, I do this:

app.component.ts

callAnotherFunction(User);

How can I do this if I have the class name as a string, that is "User"? If possible, how would I check if the variable really is a usable class?

For example:

let test = "User";

if (**test is really a usable class**) {
    console.log("Yay!");
    callAnotherFunction(**something to put here**);
} else {
    console.log("Error!");
}

I am not sure if this is even possible, but thanks for your input already.

---

All I have found so far is examples like these:

let test = "User";
let user = new window[test]();

But user would then be an instance of User. Additionally, it does not seem to work in my Angular 2 application - probably a scope error. If I wanted to try this, what would I need to use instead of window?

Solution

This sounds like a reflection question in typescript.

Possibly you could check this out if you haven't

Dynamically loading a typescript class (reflection for typescript)

Comments

[andreas]

Yes I have already read this, thank you. The examples work for me, but I would like to get the class instead of the instance. In my example above, for window["String"] it works as expected. But as my custom class User is not in window, I cannot access it. How could I access it so i can do window["User"] or something similar?

[Nico]

did you also see: stackoverflow.com/a/38127705/1804189 and stackoverflow.com/a/35787628/1804189 They explain how it can be done in Typescript 1.8+

[andreas]

Yes, my main problem now seems to be to find out the namespace that User lives in. I followed the usual Angular 2 patterns and there you don't explicitely define namespaces.

[Paritosh]

@andreas - were you able to get typescript type from the string using the usual Angular 2 patterns? please provide the any helpful link, I wasn't able to with links provided by Nico