It will most helpful
Dr Google is your friend:
https://developers.arcgis.com/javascript/3/jshelp/intro_firstmap_amd.html
http://help.arcgis.com/en/webapi/javascript/arcgis../jstutorials/
https://www.google.com/search?q=arcgis+javascript+tutorial&rlz=1C1GCEA_enUS763US763&source=lnms&tbm=...
Anupam Sharma,
ESRI has a many free videos at their E360 site. As Joe Borgione noted above, Google and YouTube will be your best friends as well.
https://www.esri.com/training/catalog/580fc1dea4a46d172b116049/basics-of-javascript-web-apps/