Added support for constructing from ArrayBuffer and added test that verifies support

[robskillington]

No description provided.

[feross]

Thanks for the PR! I would like to accept this, but I'm very hesitant for the reasons mentioned here: #39 (comment)

[feross]

It's actually not enough to just set the length correctly. subject itself should be wrapped in a Uint8Array so the data can actually be pulled out.

[robskillington]

Thanks and apologies for not seeing other issues similar to this =]

[feross]

No problem. :) I'd open an issue with websocket-stream if you still think there's a bug here, though I expect you could just do new Buffer(new Uint8Array(arraybuffer)) in your own code.

[robskillington]

So specifically mows which is an MQTT over WebSocket adapter is explicitly providing Uint8Array as the buffer type that websocket-stream should use: https://github.com/mcollina/mows/blob/master/buildWebsocketBrowser.js

This means it will new Uint8Array(incomingDataAsArrayBufferInstance) and then all the code therein breaks as websocket-stream is expecting a Nodejs Buffer API compatible buffer. Herein I updated to use just straight up Buffer using your fantastic work =] However I can't just provide type Buffer because this cannot build a Buffer from an ArrayBuffer. Hence here is my solution which I should ship back to mows now likely:

opts.type = BufferPatched;
//...
function BufferPatched(subject) {
    if (subject instanceof ArrayBuffer) {
        subject = new Uint8Array(subject);
    }
    return Buffer.apply(this, arguments);
}

util.inherits(BufferPatched, Buffer);

[feross]

This sounds like reasonable solution to me :)

[robskillington]

Just thinking: would adding to the constructor of Buffer in this library add ArrayBuffer support for everyone?

    if (typeof ArrayBuffer === 'function' && subject instanceof ArrayBuffer) {
        subject = new Uint8Array(subject);
    }

[feross]

It would, and it's tempting to add it. But I'm worried that people would write code that depends on this behavior when it won't work in node.js. Maybe I should just send a PR to node core since this is an annoying API issue that keeps coming up.

[feross]

We can add support for this feature now that node.js#next has support! nodejs/node#2002

[feross]

ArrayBuffer can be passed into the constructor as of buffer 3.4.0.