How to calculate quaternion from world position of 3 points on a plane

Of course, extracting the components of the basis vectors into constant values is equivalent to a matrix. But this also within the function. One saves the creation of the matrix in the application code. With the quaternion it seems clearer to myself.

For ‘historical’ reasons I also like to work component-wise with vectors and matrices.
There are hardly any in my
Addon. Produces almost infinite many time-varying geometries with functions
THREEf.js/THREEf.js at cc28a353fe8e3a6e98956dc299d1762b178ad452 · hofk/THREEf.js · GitHub

A little more in other addons.