Node.js COM interop

$3

Installation

``
npm install cominterop
`

Only compatible with Windows (which goes to most typelibs too anyway).

Usage

`
let cominterop = require( 'cominterop' );
let lib = cominterop.load( 'path/to/typelib.dll' );

// Normal constructors.
let obj = new lib.MyClass();

// propget/propput methods mapped to JavaScript getters/setters.
let value = obj.Value;

// Objects have a hidden .Async property which exposes a promise interface.
obj.Async.GetItem()
.then( item => {
console.log( item.Value );
} );
`

Caveats

- Pointer return values won't work maintain identity: obj.Member !== obj.Member,
when Member is non-primitive.
- Support for several data types missing. SAFE_ARRAY the biggest one.
- Only getters supported for indexed properties: arr[ 0 ].
- Uses IDispatch for method invocation.
- My current test libraries are limited to M-Files API.
Other libraries may be completely incompatible without me knowing about it.

Future plans

- Track pointers and return same references for equal pointer values.
- Add compatibility option to load()` for mangling the member names for lower
case. The upper case method names will confuse linters that expect these to
be constructors.

Performance

Preprocessing the type library should help a bit with the major performance
issues of going with raw IDispatch.

However there are still a lot of dynamic lookups happening - especially in
parameter resolution. And the method invocations are done over IDispatch (with
all the VARIANTing) instead of using direct COM vtables and other internals.