Gulp + Duo + Browsersync + Uglify

gistfile1.js

var gulp        = require('gulp');
var browserSync = require('browser-sync').create();
var uglify      = require('gulp-uglify');
var exec        = require('child_process').exec;
var srcDir      = './src/**/*.js';
var jsIn        = './src/main.js';
var jsOut       = './build/main.js';

gulp.task('default', ['browser-sync', 'duo', 'watch']);

gulp.task('browser-sync', function() {
    browserSync.init({
        proxy: "screencast-duo.app",
        notify: false
    });
});

/**
* Pega o arquivo gerado pelo Duo e minifica
*/
gulp.task('compress', function()
{
  return gulp.src(jsOut)
    .pipe(uglify())
    .pipe(gulp.dest('dist'));
});

/**
* Compila main.js (ver var jsIn acima) usando Duo.
*/
gulp.task('duo', function()
{
    exec('duo --stdout ' + jsIn + ' > ' + jsOut, function (err, stdout, stderr)
    {
        console.log(err);
        console.log(stdout);
        console.log(stderr);
    });
});

/**
*
*/
gulp.task('watch', function() {

    gulp.watch(["**/*.html"]).on('change', browserSync.reload);

    /**
    * Sempre que o arquivo compilado pelo Duo for salvo, minifica e atualiza o browser
    */
    gulp.watch([jsOut], ['compress']).on('change', browserSync.reload);

    /**
    * Observa qualquer arquivo na pasta /src
    */
    gulp.watch([srcDir], ['duo']);
});