repeatingbeats/requirejs.md

## requirejs.md

      
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              requirejs.md
            
          
    Earlier today, I tweeted 'requirejs, why so complicated?' [1]
To add some context, I'm working on a project that involves relatively complex pipelining of static assets, and I'm investigating use of the RequireJS optimizer programmatically [2] to handle the part of the process that bundles related JS modules into bundled scripts to be passed down the pipeline for minification, fingerprinting, and deployment.
In retrospect, the answer to my flippant tweet is "because the tool solves a lot of complicated problems", but it took a while to back out from a long description of the various configuration options [3] to the options that were relevant to my problem. In particular, I felt it would have been helpful to have required options called out first, as I spent a while with a baseUrl assuming that all the js files in that dir would be optimized into the output. Instead, I got a cryptic Cannot read property '0' of undefined error.
I eventually realized that I needed to provide at least one module to optimize explicitly, and once I used the name option I was able to get a build working. Perhaps it would be helpful to have better errors for common bad input cases?
Also, as a bit of a nit on the Node.js optimize method, I think the use of a method signature that takes a callback that does not in fact appear to be invoked asynchronously is a bit confusing. Even if the underlying code is not going to use async I/O for file reading and writing, it would be more idiomatic for the callback to pass errors as the first argument instead of throwing errors. Since I'm calling the optimizer inside an async handler that is upstream of requirejs in my pipeline, I have do do something like:
var foo = function (config, callback) {

  try {
    requirejs.optimize(config, function (resp) {
      callback(null, resp);
    });
  }
  catch (e) {
    callback(e);
  }

};
If errors were passed to the callback instead of thrown by the method, that would simplify to:
var foo = function (config, callback) {
  requirejs.optimize(config, function (err, resp) {
    callback(err, resp);
  });
});
To be fair, my use case of invoking the optimizer deep inside another program instead of in a single-pass build script is probably not the typical use case.
[1] https://twitter.com/#!/repeatingbeats/status/194847966106882049
[2] http://requirejs.org/docs/node.html#optimizer
[3] https://github.com/jrburke/r.js/blob/master/build/example.build.js