Cannot set Type of module.exports using JSDocs

[mjbvz]

From: microsoft/vscode#24657

TypeScript Version: 2.3.1-insiders

Code

For the JavaScript:

class Foo { }

/**
 * @type {Foo}
 */
module.exports = {}

/**
 * @type {Foo}
 */
const exp = {}

Expected behavior:
The type of module.exports and exp are both Foo

Actual behavior:
The type of module.exports is any. The type of exp is Foo

[Jessidhia]

The problem here is that @type applies only to var/let/const declarations, not to expressions. It also doesn't work for setting the type of an object key, for example:

// @ts-check

const foo = {
  /** @type {string|null} */
  bar: null
}
foo.bar = '' // type error

[mhegazy]

module.exports = {} is not a declaration, it is just an assignment, and you can have multiple of these in a single file.

@Kovensky's suggestion is more attainable. keeping this issue open to enable that.

[mhegazy]

#13306 is already tracking @Kovensky's suggestion.