gulpfile.js
function(dest, src) {
  return gulp.src(src)
    .pipe(sourcemaps.init())
    .pipe(concat(dest))
    .pipe(gulp.dest(path.join('dist', 'js')))
    .pipe(uglify())
    .pipe(rename({suffix: '.min'}))
    .pipe(sourcemaps.write('.'))
    .pipe(gulp.dest(path.join('dist', 'js')));
}
function(dest, src) {
  return gulp.src(src)
    .pipe(sourcemaps.init())
    .pipe(concat(dest))
    .pipe(gulp.dest(path.join('dist', 'js')))
    .pipe(uglify())
    .pipe(rename({suffix: '.min'}))
    .pipe(sourcemaps.write('.'))
    .pipe(gulp.dest(path.join('dist', 'js')));
}
/* ====================================================================
=            Compile and minify js generating source maps            =
====================================================================