The ArcGIS JavaScript API has an active community of developers who are willing to help you along the way. ESRI has blogs where they post updates, and host meetups in various cities across the country and around the globe. Many ArcGIS JavaScript developers, both inside and outside of ESRI, are active on Twitter and other social media outlets.
Note
You can find many resources to help you learn about the ArcGIS JavaScript API through books and the web. For books, you can check out Building Web and Mobile ArcGIS Server Applications with JavaScript by Eric Pimpler, Building Web Applications with ArcGIS by Hussein Nasser, and ArcGIS Web Development by Rene Rubalcava. For online resources, you can visit ESRI GeoNet (https://geonet.esri.com/community/developers/content), view the arcgis-javascript-api tag on GIS StackExchange (http://gis.stackexchange.com/questions/tagged/arcgis-javascript-api), or visit the ESRI GitHub page (https://github.com/esri).