This article will help you to create a SharePoint WebPart using the new Framework SPFx and the PnP JS Core. My first though was how populate my PropertyPaneDropdown in the Properties Panel. After some research, there is and Interface, the IPropertyPaneDropdownOption that must be imported from the preview of ‘@microsoft/sp-client-preview’ This is great because you can populate OnInit before the DOM render. The other big deal is CRUD among Typescript. SPFx is flexibly enough to use your favorite Framework, but the preferred is React. All source code is in my Repository on GitHub, if i need help somehow please, comment here or Clone my project for SPFx demos CLONE
git clone https://github.com/jtlivio/jl-spfx-project-webparts.git
INSTRUCTIONS
https://github.com/jtlivio/jl-spfx-project-webparts
DEMO