Precompile option

[bjoerge]

Here's a suggested fix for #31 / #32

Introduced a precompile setting that can be set according to the version (directory, file or modules):

This is how to use it:

// Precompile a single file in a directory
app.use('/js', browserify('./client/dir', {
  cache: true,
  precompile: 'beep.js'
}));

// Precompile multiple files in a directory
app.use('/js', browserify('./client/dir', {
  cache: true,
  precompile: ["beep.js", "subdir/boop.js"]
}));

// Precompile a browserified file at a path
app.get('/js/file.js', browserify('./client/file.js', {
  cache: true,
  precompile: true
}));

// Precompile a bundle exposing `require` for a few npm packages.
app.get('/js/bundle.js', browserify(['hyperquest', 'concat-stream'], {
  cache: true,
  precompile: true
}));

A few things to consider:

• Precompiling is disabled in all environments by default
• For the directory version you must opt-in on the bundles you want precompiled, as precompiling all files in a directory will potentially be overly expensive (as noted by @ForbesLindesay in #31). I have a feeling that opting in will cover the most common use cases anyways.
• It only makes sense to precompile if caching is enabled. The precompile option is ignored if !settings.cache

Any suggestions/improvements are welcome :-)

[ForbesLindesay]

The diff seems to be a bit messed up, which is making this tricky to review. I also think it looks like you've got your arrays vs. strings mixed up a little. modules is an array, so won't work if you pass it to path.resolve. Also, all paths should already be resolved before they get to the precompile function since they get resolved in index.js. Another thing I noted is that the documentation seems to suggest you can pass a string when using it for a folder but the folder code seems to assume it's an array.

[bjoerge]

Yeah, line endings got messed up. Sorry about that. I've fixed it now.

About string vs array in the configuration option: Since options.precompile is passed through arrayify in settings.normalize, (like settings.noParse, etc), it should work both with strings and arrays.

It will also work with booleans for modules and files since using precompile: true will be normalized to [true] (which is just checked for truthyness later on). At the same time, passing false to arrayify will be normalized to false, so that will work too. This may be a little bit too coincidental so I'm fine with changing it into something more clear & obvious.

Removed call to path.resolve, thanks for pointing out !

[ForbesLindesay]

Closing this in favour of #44