assets.js

var assets = require('./assets.json')
  , path = require('path')


var baseDir = __dirname

var Component = function(opts) {
  var self = this
  self.name = opts.name
  self.src = path.join(baseDir, opts.src)
  self.dest = path.join(baseDir, opts.dest)
  self.url = opts.url || '/' + opts.dest
}

var Lib = function(opts) {
  var self = this
  self.name = opts.name
  self.src = path.join(baseDir, opts.src)
  self.noParse = opts.noParse
  self.opts = opts.opts
}

var components = []
assets.components.forEach(function(c) {
  components.push(new Component(c))
})

var libs = []
assets.libs.forEach(function(l) {
  libs.push(new Lib(l))
})

var libsMeta = {
    name: assets.libsMeta.name
  , dest: path.join(baseDir, assets.libsMeta.dest)
  , url: assets.libs.url || '/' + assets.libsMeta.dest
}


exports.components = components
exports.libs = libs
exports.libsMeta = libsMeta

assets.json

{
  "components": [
      {"name": "admin", "src": "components/admin.js", "dest": "static/build/admin.bundle.js"}
  ],
  "libs": [
      {"name": "jquery", "src": "bower_components/jquery/jquery.js", "noParse": true, "opts": {"expose": "jquery"}}
    , {"name": "showdown", "src": "bower_components/showdown/src/showdown.js", "opts": {"expose": "showdown"}}
    , {"name": "backbone", "src": "bower_components/backbone/backbone.js", "opts": {"expose": "backbone"}}
    , {"name": "react", "src": "bower_components/react/react.js", "noParse": true, "opts": {"expose": "react"}}
  ],
  "libsMeta": {
      "name": "libs"
    , "dest": "static/build/libs.bundle.js"
  }
}

bundle.js

#!/usr/bin/env node

var fs = require('fs')
  , browserify = require('browserify')
  , watchify = require('watchify')
  , reactify = require('reactify').process
  , UglifyJS = require('uglify-js')
  , db = require('../db')
  , crypto = require('crypto')
  , async = require('async')
  , components = require('../assets').components
  , libs = require('../assets').libs
  , libsMeta = require('../assets').libsMeta


var bundleQue = async.queue(function(opts, callback) {
  opts.br.bundle({debug: opts.debug}, function(err, code) {
    if (err) {
      if (opts.debug) {
        console.error(String(err))
        return
      } else {
        throw err
      }
    }
    var sum = crypto.createHash('md5')
      , msg = ' with source maps.'
    if (!opts.debug) {
      code = UglifyJS.minify(code, {fromString: true}).code
      var msg = ''
    }
    fs.writeFile(opts.dest, code, function(err) {
      if (err) throw err
      console.log('Wrote ' + opts.dest + msg)
      sum.update(code)
      db.rediscli.hset('bundles', opts.name, sum.digest('hex'), function(err) {
        if (err) throw err
        callback()
      })
    })
  })
}, 4)



var bundleLibs = function(debug) {
  var noParse = []
  libs.forEach(function(lib) {
    if (lib.noParse) {
      noParse.push(lib.src)
    }
  })
  var br = browserify({noParse: noParse})
  libs.forEach(function(lib) {
    br.require(lib.src, lib.opts)
  })
  bundleQue.push({br: br, name: libsMeta.name, dest: libsMeta.dest, debug: debug})
}


var bundleComponent = function(c, debug) {
  var br = browserify(c.src)
  libs.forEach(function(lib) {
    br.external(lib.name)
  })
  br.transform(reactify)
  bundleQue.push({br: br, name: c.name, dest: c.dest, debug: debug})
}


var listenComponent = function(c, debug) {
  var w = watchify(c.src)
  libs.forEach(function(lib) {
    w.external(lib.name)
  })
  w.transform(reactify)
  w.on('update', function() {
    bundleQue.push({br: w, name: c.name, dest: c.dest, debug: debug})
  })
  bundleQue.push({br: w, name: c.name, dest: c.dest, debug: debug})
}


var bundle = function(all, debug) {
  if (all) {
    bundleLibs(debug)
  }
  components.forEach(function(c) {
    bundleComponent(c, debug)
  })
  bundleQue.drain = function() { db.close() }
}


var listen = function(debug) {
  components.forEach(function(c) {
    listenComponent(c, debug)
  })
}


if (require.main === module) {
  var argv = require('optimist').argv
  if (argv.listen) {
    listen(true)
  } else {
    bundle(argv.all, !!argv.debug)
  }
}


exports.bundle = bundle
exports.listen = listen

middleware.js

...
exports.bundles = function(req, res, next) {
  db.rediscli.hgetall('bundles', function(err, hash) {
    res.locals.bundles = res.locals.bundles || {}
    var updateLocals = function(name, url) {
        var v = hash[name] ? '?' + hash[name] : ''
        res.locals.bundles[name] = '<script src="' + url + v + '"></script>'
    }
    updateLocals(assets.libsMeta.name, assets.libsMeta.url)
    assets.components.forEach(function(c){
      updateLocals(c.name, c.url)
    })
    next()
  })
}
...