You should have a broad range, so you can fix css issues, javascript frontend issues as well as build a new feature that integrates with a database.
As shown above, but basically you can code a web app from start to finish (e.g. backend code/framework like ruby on rails, frontend like css/html/etc and integrate some time of database (e.g. MySQL or Mongo).
As shown above, but basically you can code a web app from start to finish (e.g. backend code/framework like ruby on rails, frontend like css/html/etc and integrate some time of database (e.g. MySQL or Mongo).