Interesting and useful gulp snippets.

gulpfile-env.js

/*

From https://github.com/gulpjs/gulp/issues/101. Organize gulpfile.js using concept of environment variables.

1. Set up sub-tasks to behave in a certain according to env var; may be env agnostic.
2. Set up high-level tasks to run a group of sub-tasks to orchestrate a behaviour (testing, staging, prod, etc)
*/
var R = 0;
var ENV_SWITCH = void 0;

// define env
var DEV_ENV = R++;
var PROD_ENV = R++;

// Transformation function on gulp.src depending on env
var getGlob = function(env, glob_target) {
  var src = gulp.src(glob_target);

  switch(env) {
    case DEV_ENV:
      return src.pipe(watch());
    case PROD_ENV:
      return src;
    default:
      throw new Error('Invalid Env');
  }
}

/*
Tasks that describe build subroutines. Task names can be thought of as categories.

Set up subroutines to behave depending on ENV_SWITCH. 
You do this so you don't need to repeat code at a higher task-level.
*/

gulp.task('vendor-scripts', function() {

  gulp.src('client/js/vendor/**')
    .pipe(gulp.dest('build/js/vendor'));

});

gulp.task('project-scripts', function() {

  getGlob(ENV_SWITCH, ['client/js/**/*.js', '!client/js/vendor/**'])
    .pipe(uglify())
    .pipe(gulp.dest('build/js'));

});

gulp.task('assets', function() {

  getGlob(ENV_SWITCH, 'client/img/**')
    .pipe(gulp.dest('build/img'));

  getGlob(ENV_SWITCH, 'client/css/**')
    .pipe(gulp.dest('build/css'));

  getGlob(ENV_SWITCH, 'client/*.html')
    .pipe(gulp.dest('build'));

});


// High-level tasks that compose build subroutines to orchestrate a behaviour.

gulp.task('prod', function() {

  ENV_SWITCH = PROD_ENV;

  // Run categorical sub-tasks
  gulp.run('vendor-scripts' 'project-scripts', 'assets');  

});

gulp.task('dev', function() {

  ENV_SWITCH = DEV_ENV;

  gulp.run('project-scripts', 'assets');

});

gulp.task('test', function() {

  ENV_SWITCH = TEST_ENV;

  // To be set up...

});