Allow optional property syntax, similar to typescript with key?: value

[gkielyellation]

It would be great for users coming from typescript to be able to write the following:

type ObjectType = {
  key?: string
}

const test: ObjectType = {};

Thanks.

[JSMonk]

Hi @gkielyellation.
You will have the same behavior if you will move the question mark after : like this:

type ObjectType = {
  key: ?string
}

const test: ObjectType = {};

But in the next version (Hegel 2) we will use TypeScript syntax :)

[charlag]

@JSMonk isn't it significant whether the key is present or not?

[JSMonk]

I think that, If the developer defined the property as undefinedable, it means that it thinks that the property can be inside the object, so, in the case there is no difference, because in both case, at the static time, the result will be undefined.
The only difference will be when we use in operator.

[thecotne]

Object.keys and Object.entries also give different results when prop is not there vs when prop is undefined

[JSMonk]

It's true. And also we infer the keys result from the object type.