using Interface to express object in Typescript types declaration

Question

I'm writing types declaration for a framework, for a function, it has a parameter whose type is object, but I want to describe it using interface in the declaration type like this:

interface Options{
    template: string | Selector | AST;
    config (data: object): void;
}

interface Regular_Static {
    new (options: Options): Regular_Instance;
    // todo
}
declare var Regular: Regular_Static;

export = Regular

But when I write like this in my application:

class HelloRegular extends Regular {
    constructor(options: object){
        super(options);
    }
}

it shows that type object can't be assignment to type Options. So how to do with it?

supplement: The Options type declaration can't be got in application unless we declare it in our application. I mean to let the Options do like an object.

If the constructor for Regular_Static expects an object with template and config why would the compiler allow you to call the constructor (as super(options)) with an object that may not have those properties ? — Titian Cernicova-Dragomir
– Titian Cernicova-Dragomir, Commented Apr 3, 2018 at 13:26
So what happens when you change options: object to options: Options? — enf0rcer
– enf0rcer, Commented Apr 3, 2018 at 13:26
@TitianCernicova-Dragomir There is no type Options in application — laoqiren
– laoqiren, Commented Apr 3, 2018 at 13:34
@laoqiren you define the type in the declarations, it's an interface, it does not need an implementation, so you can use it, as people have done in the answers :) — Titian Cernicova-Dragomir
– Titian Cernicova-Dragomir, Commented Apr 3, 2018 at 13:35

Jonas Wilms · Accepted Answer · 2018-04-03 13:30:04Z

1

Take the proper type here:

interface Options{
  template: string | Selector | AST;
  config (data: object): void;
}

class HelloRegular extends Regular {
  constructor(options: Options){
    super(options);
  }
}

edited Apr 3, 2018 at 13:30

answered Apr 3, 2018 at 13:27

Jonas Wilms

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2 Comments

laoqiren Over a year ago

But the Options type declaration is not in the application and it is only at the declaration type file.

Jonas Wilms Over a year ago

@laoqiren no problem as ts got duck typing.

DJAMEL DAHMANE · Accepted Answer · 2018-04-03 13:34:47Z

0

you can import that interface to you class like that

      export interface Options{
             template: string | Selector | AST;
             config (data: object): void;
    }

      export interface Regular_Static {
           new (options: Options): Regular_Instance;
        // todo
                 }

and here import that interface and class to use it

    import { Options, Regular_Static} from 'yourfile.ts';
    class HelloRegular extends Regular {
          constructor(options: Options){
           super(options);
            }
        }

answered Apr 3, 2018 at 13:34

DJAMEL DAHMANE

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