Using the Web AppBuilder Web AppBuilder Custom Widgets Web AppBuilder for ArcGIS
There is not that I have seen.
There are no types for jimu. However for those who still wish to use typescript you can declare like so at the top of your ts file.
/// <amd-dependency path="jimu/BaseWidget" name="BaseWidget" />declare var BaseWidget: any; // there is no ts definition of BaseWidget yet
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