Gulp starter for JS

gulpfile.js

var gulp   = require('gulp');
var rename = require('gulp-rename');
var uglify = require('gulp-uglify');

gulp.task('js', function () {
    return gulp.src('assets/js/**/*.js') //select all javascript files under js/ and any subdirectory
        .pipe(uglify())
        .pipe(rename({ suffix: '.min' }))
        .pipe(gulp.dest('assets/js/')); //the destination folder
});

// Watch Files For Changes
gulp.task('watch', function() {
    gulp.watch('js/**/*.js', ['js']);
});

// Default Task
gulp.task('default', ['js', 'watch']);

function swallowError (error) {
    //If you want details of the error in the console
    console.log(error.toString());
    this.emit('end');
}

pre-script.sh

# with Node.js and NPM installed
# install gulp and gulp packages
npm install gulp gulp-rename gulp-uglify