If you'd like to learn the basics about the ArcGIS API 4 for JavaScript, check out this 1-hour training seminar that Rene Rubalcava and I did last week.
Discover the Next-Generation ArcGIS API 4 for JavaScript
The goals of this session were to help you get started on:
This is awesome, I missed the seminar and I really wanted to attend that.
If you watched the presentation and would like the demos..
Rene Rubalcava has shared his demos here: https://github.com/odoe/esri-lts/tree/master/esrijs-discover-4
I showed the following SDK samples:
https://developers.arcgis.com/javascript/latest/sample-code/scene-local/live/index.html
https://developers.arcgis.com/javascript/latest/sample-code/symbols-points-3d/live/index.html
https://developers.arcgis.com/javascript/latest/sample-code/layers-scenelayer/live/index.html
https://developers.arcgis.com/javascript/latest/sample-code/visualization-vv-color/index.html
https://developers.arcgis.com/javascript/latest/sample-code/layers-portal/live/index.html
https://developers.arcgis.com/javascript/latest/sample-code/portalitem-dragndrop/live/index.html
https://developers.arcgis.com/javascript/latest/sample-code/webscene-basic/live/index.html
https://developers.arcgis.com/javascript/latest/sample-code/webscene-slides/live/index.html
Added all to the Web AppBuilder Developer Edition - Customization Resource List as I think it will be of interest to many there.