How to use vec2/3 classes

Hello, as I restarted using JSCAD, after a long time using only C language, then vanilla JS, I would like to know how to use the vec2/3 classes, what is the needed require, and how to use them. I remember I used such classes with V1 but with V2 I didn't and for exemple I have code where I need to compute a geometry dimensions and center, so I use
b = measureBoundingBox()
then the dimensions are b[1] minus b[0]
and the center is b[1] minus dimensions' half
For the moment I'm directly using the values from the returned array. 
@gilboonet the example looks fine. You can create, rotate, transform all the math objects..
Now comes the fun part... curves, distances, etc. There are little tidbits of logic throughout the library. You can find some of the basic calculations in the primitives, I.e. arc, circle, sphere, etc.
And of course, let us know if you have questions.

Just to reply to my own question ...
const jscad = require('@jscad/modeling') const { sphere } = jscad.primitives const { vec3 } = jscad.maths const { translate } = jscad.transforms const main = () => { let A = vec3.fromValues(15,0,5); console.log("A:", A); let B = vec3.create(); vec3.add(B, A, [50,0,0]); console.log("B:", B); let C = vec3.create(); vec3.add(C, A, B); vec3.divide(C, C, [2,2,2]); return [ translate(A, sphere({radius:2})) , translate(B, sphere({radius:2})) , translate(C, sphere({radius:1})) ]; } module.exports = { main }