Gulp + Babel + import

gulpfile.js

gulp.task('scripts:search', () => {
    return gulp.src('./search-module/index.js', { read: false })
        .pipe(tap((file) => {
            file.contents = browserify(file.path, {
                debug: true
            }).transform(babel, {
                presets: ["es2015"],
                plugins: ["angularjs-annotate"]
            }).bundle();
        }))
        .pipe(buffer())
        .pipe(gulpif(build, uglify({mangle: build, compress: build})))
        .pipe(concat('search.js'))
        .pipe(gulp.dest('wordpress-theme/assets/search-module/'));
});