using `npm run` to build and watch with node-sass and browserify

package.json

{
  "name": "my-app",
  "version": "0.0.0",
  "devDependencies": {
    "browserify": "^10.2.4",
    "watchify": "^3.2.3",
    "node-sass": "^3.2.0",
    "uglify": "^2.4.23",
    "mkdirp": "^0.5.1",
    "parallelshell": "^1.2.0",
    "rimraf": "^2.4.1"
  },
  "scripts": {
    "build-sass": "mkdirp static/stylesheets && node-sass stylesheets/index.scss static/stylesheets/bundle.css",
    "watch-sass": "mkdirp static/stylesheets && node-sass -wr stylesheets/*.scss' -o static/stylesheets/bundle.css -v",
    "build-js": "mkdirp static/javascripts && browserify browser/*.js | uglifyjs -o static/javascripts/bundle.js",
    "watch-js": "mkdirp static/javascripts && watchify browser/*.js -o static/javascripts/bundle.js -dv",
    "build": "parallelshell 'npm run build-sass' 'npm run build-js'",
    "watch": "parallelshell 'npm run watch-sass' 'npm run watch-js'",
    "clean": "rimraf static",
  }
}