Example gulp file

gulp

// Include gulp
var gulp = require('gulp');

// Include Our Plugins

var sass = require('gulp-sass');
var concat = require('gulp-concat');
var uglify = require('gulp-uglify');
var rename = require('gulp-rename');
var autoprefixer = require('gulp-autoprefixer');
var minifycss = require('gulp-minify-css');
var uglify = require('gulp-uglify');
var rename = require('gulp-rename');
var concat = require('gulp-concat');
var notify = require('gulp-notify');


// Compile Our Sass
gulp.task('sass', function() {
    return gulp.src('library/scss/style.scss')
        .pipe(sass({style: 'expanded'}))
        .pipe(autoprefixer('last 1 version'))
        .pipe(gulp.dest('library/css'))
        .pipe(rename({suffix: '.min'}))
        .pipe(minifycss())
        .pipe(gulp.dest('library/css'))
        .pipe(notify({ message: 'Styles task complete' }));

});

// Minimify & Concat Our Scripts

gulp.task('scripts', function() {
  return gulp.src('library/js/plugins/*.js')
    .pipe(concat('main.js'))
    .pipe(gulp.dest('library/js/build'))
    .pipe(rename({suffix: '.min'}))
    .pipe(uglify())
    .pipe(gulp.dest('library/js/build'))
    .pipe(notify({ message: 'Scripts task complete' }));
});


gulp.task('watch', function() {
    // calls "sass" whenever anything changes
    gulp.watch("library/scss/*.scss", ["sass"]);
    gulp.watch("library/js/plugins/*.js", ["scripts"]);
});


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