gulpfile.js

var gulp        = require('gulp');
var sass        = require('gulp-sass');
var concat      = require('gulp-concat');
var uglify      = require('gulp-uglify');
var runSequence = require('run-sequence');

gulp.task('libs', function() {
  return gulp.src('node_modules/jquery/dist/jquery.min.js')
    .pipe(gulp.dest('build/libs'));
});

gulp.task('html', function() {
  return gulp.src('src/*.html')
    .pipe(gulp.dest('build'));
});

gulp.task('images', function() {
  return gulp.src('src/images/**/*.png')
    .pipe(gulp.dest('build/images'));
});

gulp.task('sass', function() {
  return gulp.src('src/scss/**/*.scss')
    .pipe(sass())
    .pipe(concat('styles.css'))
    .pipe(gulp.dest('build/css'));
});

gulp.task('scripts', function() {
  return gulp.src('src/scripts/**/*.js')
    .pipe(gulp.dest('build/scripts'));
});

gulp.task('watch', ['html', 'sass', 'scripts', 'images'], function() {
  gulp.watch('src/*.html', ['html']);
  gulp.watch('src/scss/**/*.scss', ['sass']);
  gulp.watch('src/scripts/**/*.js', ['scripts']);
});

gulp.task('build', function() {
  runSequence('libs','html', 'sass', 'scripts', 'images');
});

gulp.task('default', ['build', 'watch']);