Браузер синк не прослушивает изменения JS в чем проблема?

Есть два режима в сборке продакшн и разработке.Подключаю слайдер и библиотеки но в браузерсинк изменений нет а если index.html запускаю из продакшн то все хорошо в чем ошибка?
~~~~~~~~~~~~~gulpfile~~~~~~~~~~~~~~~~~~~~

const gulp = require('gulp');
const autoprefixer = require('gulp-autoprefixer');
const del = require('del');
const browserSync = require('browser-sync').create();
const cleanCSS = require('gulp-clean-css');
const sourcemaps = require('gulp-sourcemaps');
const gulpif = require('gulp-if');
const gcmq = require('gulp-group-css-media-queries');
const smartgrid = require('smart-grid');
const sass = require('gulp-sass');
const webpack = require('webpack');
const webpackStream = require('webpack-stream');
const isDev = (process.argv.indexOf('--dev') !== -1);
const isProd = !isDev;
const isSync = (process.argv.indexOf('--sync') !== -1);




function clear(){
	return del('build/*');
};

function styles(){
	return gulp.src('./src/css/styles.sass')
			   .pipe(gulpif(isDev, sourcemaps.init()))
			   .pipe(sass())
			   
			   .pipe(gcmq())
			   .pipe(autoprefixer({
		            browsers: ['> 0.1%'],
		            cascade: false
		        }))
			   //.on('error', console.error.bind(console))
			   .pipe(gulpif(isProd, cleanCSS({
			   		level: 2
			   })))
			   .pipe(gulpif(isDev, sourcemaps.write()))
			   .pipe(gulp.dest('./build/css'))
			   .pipe(gulpif(isSync, browserSync.stream()));
};

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

function html(){
	return gulp.src('./src/*.html')
			   .pipe(gulp.dest('./build'))
			   .pipe(gulpif(isSync, browserSync.stream()));
};

const webpackConfig = require("./webpack.config.js");

function scripts() {
    return gulp.src("./src/js/index.js")
        .pipe(webpackStream(webpackConfig), webpack)
        //.pipe(gulpif(production, rename({
         //   suffix: ".min"
       // })))
        .pipe(gulp.dest("./build/js/"))
        //.pipe(debug({
        //    "title": "JS files"
        //}))
        .on("end", browserSync.reload);
};

function watch(){
	if(isSync){
		browserSync.init({
	        server: {
	            baseDir: "./build/",
	        }
	    });
	}

	gulp.watch('./src/css/**/*.sass', styles);
	gulp.watch('./src/**/*.html', html);
	gulp.watch('./smartgrid.js', grid);
};

function grid(done){
	delete require.cache[require.resolve('./smartgrid.js')];

	let settings = require('./smartgrid.js');
	smartgrid('./src/css', settings);

	done();
}

let build = gulp.series(clear, 
	gulp.parallel(scripts, styles, img, html)
);

gulp.task('build', build);
gulp.task('watch', gulp.series(build, watch));
gulp.task('grid', grid);