JS IntelliSense doesn't show members if class inherits from multiple types about typescript

[RyanCavanaugh]

extends in this position is only really for adding type arguments. It can't be used to make an extends clause where one doesn't exist.

[Kebab11noel]

But then how should I document it to get member suggestions from multiple parents?

[jakebailey]

JS doesn't have multiple inheritance; how can a class extend B if it already extends A?

[Kebab11noel]

Well technically it doesn't extend it, but has the members.
In my use case I have an APIBase class that handles a WebSocket connection and events by extending EventTarget, I also have another class that serves as an interface which holds methods that are implemented on the server side and I have a Proxy targeting the APIBase to handle creating functions for RPC. I want to document this proxy instance in a way that would provide suggestions for the base members and also the RPC methods that are created on the fly by the proxy.

[jakebailey]

@extends is fundamentally intended to model exactly class extends; what you're describing is something else which would probably be modelled better with implements or a type cast.

[Kebab11noel]

I totally forgot that @implements exists, but sadly that doesn't work either.

class A {foo(){}}
/** @interface */
class B {bar(){}}

/**
 * @implements {B}
 */
class C5 extends A {baz(){}}
new C5()//. will suggest: baz, foo -> missing: bar

/**
 * @implements {A}
 * @implements {B}
 */
class C6 {baz(){}}
new C6()//. will suggest: baz -> missing: foo, bar

[snarbies]

I don't believe that's how @implements works.

I'm very clumsy with JSDoc, but something along these lines seems to work

class A {foo(){}}
class B {bar(){}}
class MyClass_ {boop(){}}

/** @type 
 *      {(typeof MyClass_) 
 *    & {new(): (A & B & MyClass_)}} 
 * */
export const MyClass = /** @type {any} */ (MyClass_);

const myInstance = new MyClass();
myInstance //.foo(), .bar(), .boop()

[Kebab11noel]

Well it works... but it's more complex than a simple @implements. Also I tested C1-C6 in WebStorm and in every case I got the expected suggestions.

[typescript-bot]

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