Allow object to be empty on client side

[bliepp]

Hey there,

I came across your project and I really love it!

I recently realized that the Velox constructor on the client side doesn't allow for the obj parameter to be empty. Your examples use global objects like

// load script /velox.js
var foo = {};
var v = velox("/sync", foo);
v.onupdate = function() {
  //foo.A === 42 and foo.B === 21
};

As it can be seen, there are no requirements to the passed object besides being of type object.

However, since the onupdate callback passes this.obj as a parameter anyway, the object containing the received data doesn't need to be global (when using SSE, at least). Right now I'm using

var v = velox("/sync", {});
v.onupdate = function(obj) {
  //obj.A === 42 and obj.B === 21
};

to avoid using global objects, but this still looks a bit ugly. It would be better if the empty object could be omitted and instead be implicitly created by the constructor like velox("/sync").

I would therefore propose a change in the constructor of the Velox class like

obj = obj || {};
if (typeof obj !== "object") {
  throw "Invalid object";
}
this.obj = obj;

to implicitly create an empty object when the parameter obj is omitted instead of throwing an error.

Kindly
bliepp