Jan 26 2018 03:52 PM - edited Jan 26 2018 03:54 PM
That sounds like you will want to start with https://www.microsoft.com/en-us/learning/mcsa-web-applications-certification.aspx then move on to https://www.microsoft.com/en-us/learning/mcsd-app-builder-certification.aspx. Depending on you level of experience you may actually want to start with https://www.microsoft.com/en-us/learning/mta-summary-certification.aspx
Microsoft has retired their SharePoint specific developer exams.
You will also want to get familiar with the Patterns and Practice guidance (PnP) at https://dev.office.com/patterns-and-practices