addWatchers() {
        let {globals, build} = this.config;

        // use chokidar to rebuild routes
        let pagesDir = join(globals.rootDir, 'pages');
        let rebuildRoutes = debounce(async () => {
            await this.routeManager.buildRoutes();
        }, 200);
        this.addWatcher(pagesDir, ['add', 'unlink'], rebuildRoutes);

        // watch files provides by user
        if (build.watch) {
            this.addWatcher(build.watch, 'change', this.startRebuild.bind(this));
        }

        // watch lavas.config.js, rebuild whole process
        let configDir = join(globals.rootDir, LAVAS_CONFIG_FILE);
        this.addWatcher(configDir, 'change', this.startRebuild.bind(this));
    }
watch some directories and files such as /pages, lavas.config.js