Emit scrambles variables if passing 4+ parameters with a callback, in IE9.

[mGuv]

Odd title but this is a very specific issue, it seems. I've only seen this happen in Internet Explorer 9.

If you emit four or more variables with the last parameter being a function. When the function is passed through, "asyncAngularify", it also causes the third parameter (index 2) to change in to the resulting function.

E.g.

angularSocket.emit("MyEvent", dataA, dataB, dataC, someCallback);

Will get passed to socket as:

emit("MyEvent", dataA, wrappedCallback, dataC, wrappedCallback);

I believe this is a crazy issue to do with IE9s interpretation of the function. The function is defined as:

emit: function (eventName, data, callback)

Yet these parameters are never used, however, it does do:

var callback = arguments[lastIndex];

The key part here being that callback has been declared twice. Once, as parameter 3 of the arguments array (function definition) and now once as the final parameter of the arguments. So when:

callback = asyncAngularify(socket, callback);

happens, I believe it overwrites both arguments[2] and arguments[length - 1]

The fix for me so far is just to remove the variables in the function definition. Other methods would be to rename the parameters so there are no conflicting ones.

[mGuv]

Just noticed it was spotted before:

#54

However, IE9 doesn't support use strict.