Completions for private members appear in JavaScript files

[jessetrinity]

When a .d.ts file is included with a .js file (ostensibly created by some .ts file in a galaxy far far away) in order to get intellisense, private class members appear in completions lists. This is probably a bug and we have gotten some feedback from users that they would rather not see this.

A possibly greater pain point is that when the private member shows up in completion, the icon is wrong, I'm guessing because we do not have the full signature for private members in .d.ts files. I believe the lack of full signatures is by design though and I don't believe there is a way to make those members appear method-like without them.

TypeScript Version: 3.6.3

Search Terms:
private completion

Code

.d.ts

// @filename:test.d.ts
/** The 'Test' namespace. */
declare namespace Test {
    /** The 'Foo' class.*/
    class Foo {
        /** Constructor. */
        constructor();
        /** I'm private: don't use me. */
        private MethodOne;
        /** I'm public: let's do this. */
        MethodTwo(): void;
    }
}

.js

// @filename:file.js
var foo = new Test.Foo();
foo.

Expected behavior:
The completion list contains MethodTwo.

Actual behavior:
The completion list contains MethodOne and MethodTwo.

[orta]

Yeah, I agree - want to pair on this with me?

[Jolg42]

Hi there :)

So it looks like this bug is still present in the latest stable version, what is the status on your end? Would this be fixed soon maybe?

This bug is quite annoying for developer experience as a library author because it's suggesting to developers that it is fine to use the private properties (and it's adding a lot of noise to the public ones). Most people won't even know they are actually private. So if they start using them and an internal change breaks these, it will impact the users of the library, even though it's not a real breaking change in the user-facing API.

[DanielRosenwasser]

Go for it - language service tests are in tests/cases/fourslash, look for // @filename comments to create mixed a mixed .js and .ts context. The core logic is in src/services/, probably in a file called completions.ts.

[Jolg42]

Hi @jessetrinity, will this be in a future 3.9.x release maybe? Or like the milestone suggests the 4.0 August release?

[jessetrinity]

@Jolg42 it should be in 4.0.