fn with no globals

This is a JavaScript sketch, please read the disclaimers.

Background

To get some decent code reuse, we need baseline support for loading code across environments. CommonJS made a good first pass with the Modules and Packages proposals. The Module one does not work well in the browser though, so I am hoping the Async Module proposal gains traction. Douglas Crockford likes async code loading too (around 39:10 in the video).

Relying on a server to generate client-friendly code is not a universal solution, and it is a particularly poor solution for doing mobile web development, where apps can be created with HTML/CSS/JS but run from the mobile device without a server.

RequireJS implements the Async Module proposal. There are some rough spots around the Packages proposal, particularly around mappings, but it is something that can be used, and I'm trying to support some version of packages with RequireJS.

The ECMAScript folks are looking at a Simple Modules spec, but it does not solve any of the problems for me. The problems have been addressed by RequireJS. It would be nice to not to have to include the code for RequireJS in an app, but it works, it is not crazy big, and it can always be pushed down to native environment support after it is broadly in use.

fn with no globals

What I would like to see instead of a Simple Modules is "fn". It is like "function" but it does not have access to the global space. You would use it just like "function" but any variables missing "var" would not be in the global space (could throw an error). If it needs a "use fn" or something like that, OK, but I am not familiar with when "use" strings are needed. Example:

fn hello() {
   //the next line would throw
   message = 'hello';

   //the next line would be an error too
   var name = window.name;

   return message;
}

That would give me one of the big things out of Simple Modules that I cannot already have via RequireJS. It would also shorten the traditionally cumbersome "function" word and encourage good coding practice since it does not have access to the global scope. For situations that need global access, fall back to good old "function".

I would not be surprised if this has already been suggested, but as mentioned in my sketches preamble, just jotting down things as they come to me without doing due diligence.