“Loft” Feature From Fusion 360 and Solid Works in three.js | Connect two closed loops

I am trying to create a mesh object in three.js where I connected two closed shapes. Let’s say a circle and a rectangle.

and connect them together like this. It’s called the “Loft” feature in Fusion 360 and SolidWorks

I know nurbs aren’t really supported all that well in three.js. What would be your best approach to achieve this result? The shapes can be arbitrary splines.