Typings for read-write variables

[daniel-stoneuk]

Please forgive me if some of my terminology is incorrect, I'm fairly new to JXA and I haven't been able to find much documentation on it.

I'm using this project in a TypeScript application and it's working great - thank you for such a cool idea and execution.

I've run into an issue with setting read-write variables. The current typings are fine for retrieving an attribute such as .index()

const windowIndex = safariWindow.index()

But there doesn't seem like there is a way to set the attribute without TS complaining. The two ways of setting that I am aware of are

safariWindow.index = 0
safariWindow.index.set(0)

I have had a think and I don't believe we can make a TS type to satisfy both the function call getter and the direct assignment setter, so I propose new interfaces that can be added to the .d.ts files for ReadOnly and ReadWrite attributes.

e.g.

  export interface ReadWrite<T> {
    (): T;
    set: (value: T) => void;
  }

...

    index: ReadWrite<number>;

If this would be a useful and acceptable change for you, I'd be happy to do the work and make a PR.

[jakiestfu]

+1 to this