my javascript build system: more front-end shenanigans

bld.js

// $ npm i nanomsg browserify es6ify stylus
// $ node bld

const createWriteStream = require('fs').createWriteStream
const readFileSync      = require('fs').readFileSync
const writeFile         = require('fs').writeFile
const resolve           = require('path').resolve
const browserify        = require('browserify')
const join              = require('path').join
const watch             = require('fs').watch
const stat              = require('fs').stat
const stylus            = require('stylus')
const utf8              = {encoding:'utf8'}

switch (process.argv[2]) {
  case '-watch':
  case 'watch':
  case '-w':
    watch(join(__dirname, 'src'), utf8, fileChange)
    watch(join(__dirname, 'css'), utf8, fileChange)
}

var ws = createWriteStream(join(__dirname, 'dot.js')), size


/**
 * `fileChange()`
 * try to watch `vdomsite/src` for changes and call `build()` to rebuild js
 * also try to watch `vdomsite/css` for changes and call `styl()` to rebuild css
 */

function fileChange (eh, file) {
  switch (file) {
    case 'dot.js'     : return
    case 'style.css'  : return
    case 'main.styl'  : return styl()
  }
  vdom(file)
}


/**
 * `vdom ( filename )`
 * build virtual-dom javascript (from entry point src/main.js)
 * a global `b`, from which `bundle()` is called, generates new readables
 */

var b = browserify()
  .add(join(__dirname, 'src/main.js'))
  .transform(require('es6ify'))
function vdom (f) {
  var readable = b.bundle()

  stat(join(__dirname, 'dot.js'), (err, stats)=> size = stats.size)

  // i was curious to bench the stream
  // readable's `s` property is start time checked `.on('end')`
  readable.s = Date.now()

  readable
    .on('end', perf )
    .pipe(createWriteStream(join(__dirname, 'dot.js')))
    .f = f
}
function perf () {
  str = this.f ? `saved ${this.f}, rebuilt` : 'built'
  console.log(`${str} dot.js in ${Date.now() - this.s}ms`)
  if (!size)
    console.log(`now open index.html in a browser:\n
      $ open ${join(__dirname, 'index.html')}\n`)
}


/**
 * builds css from the stylus in css/main.styl
 */

function styl() {
  stylus( readFileSync( join(__dirname, 'css/main.styl'), 'utf8' ) )
    .include( join(__dirname, 'css') )
    .render( (err, css) =>
      writeFile( join(__dirname, 'css/style.css'), css ) ) // .render()
  console.log('generating new style.css')
}

vdom()
styl()


// this udp server is for receiving events from atom editor when a file saves
// lower latency than file watcher, and be sure to alleviate text editor load
const server = require('dgram').createSocket('udp4')

server.on('error', er); function er( err ) { server.close(); throw err }
server.on('listening', heard )
function heard(){
  var addr = this.address()
  console.log('server listening '+ addr.address + ':' + addr.port)
}
server.on('message', handler )

// this function will handle the buffer of our file path
function handler( buf ) {

  // parse saved file path, on windows use node's `require('path')` api
  var msg = String( buf ), s = msg.split('/');
  console.log( `saved buf: ${msg}` )
  
  // remove '','Users','reqshark' on unix/osx
  s.shift();s.shift();s.shift();s.shift();

  // look at dir names starting under the home folder
  switch(s[0]){
    // get more specific than the s[0] case, like s[1], s[2], for `myprojects` etc.
    // custom cases for local file system project directory
    // resolve only if we're in the `reqshark directory` this time
    
    case 'money'      : return r (s,require('path').resolve(msg)) // call r(file)
    
    default           : console.log('unregistered path')
  }
}

// r() reads and formats our file data as a utf8 value assigned to `d` or `data` property
// on the outbound packet published over nanomsg. `p` key for path info needed for writing,
// reassemble user's project tree later (not too long w/ nanomsg) at remote server or sub sockets
function r ( s, dir ){
//  require('fs').readFile(dir, 'utf8', function (er,dat) {
//    pub.send( JSON.stringify({p:s.join('/'),d:dat}) )
//  })
  vdom(); styl() // may want to rebuild dom/css
}
server.bind( 46000,'127.0.0.1' )