Tracking file changes within Vagrant for real-time Browserify compilation

gistfile1.txt

var async = require('async'),
	glob = require('glob'),
	browserify = require('browserify'),
	_ = require('underscore'),
	fs = require('fs'),
	scriptBytes = 0,
	compiled;

var getTotalBytes = function(patterns, cb) {
    var tasks = [],
        totalSize = 0;
    _.each(patterns, function(pattern) {
        tasks.push(function(cb) {
            glob(pattern, function(err, scripts) {
                if (err) {
                    return cb(err);
                }
                var counter = 0;
                _.each(scripts, function(script) {
                    fs.stat(script, function(err, stats) {
                        if (err) {
                            return cb(err);
                        }
                        totalSize += stats.size;
                        counter++;
                        if (counter === scripts.length) {
                            return cb(null);
                        }
                    });
                });
            });
        });
    });
    async.series(tasks, function(err, result) {
        if (err) {
            return cb(err);
        }
        return cb(null, totalSize);
    });
};

app.get('/api/js/app', function(req, res) {
    var compile = function() {
        res.set({
            'Content-Type': 'application/x-javascript'
        });
        var b = browserify({
            'basedir': '/opt/app/app/scripts',
            'commondir': '/opt/app/app/scripts'
        });
        b.transform('brfs');
        b.transform('aliasify');
        b.add('./app.js');
        var bundle = b.bundle(),
            contents = '';
        bundle.on('data', function(data) {
            data = data.toString();
            contents += data;
        });
        bundle.on('end', function() {
            compiled = contents;
            res.send(contents);
        });
    };
    getTotalBytes([
        '/opt/app/bower_components/**/*.js',
        '/opt/app/app/scripts/**/*.js'
    ], function(err, bytes) {
        if (scriptBytes === bytes) {
            res.send(compiled);
        } else {
            scriptBytes = bytes;
            compile();
        }
    });
});