Odtnhj

I'm new to SVG.js and to a concept in general, though I have a vector graphic background. So what I'm looking for is the understanding of the concept.

Duplicating, have found only the Array copy function, how to duplicate an object?
As an example:

element.rotate(45, 50, 50)

This rotates the element what if I want to keep a copy intact?

The Array itself. What is it? Doesn't looks like an Array in a graphic design program. What if I want simply to have a three raw array with five column of elements?

Merging. If I have an arc and line could I merge them to a path? Then rotate around an endpoint their copy and merge again to have the nice corners?

Maybe I ask too much but as a newcomer, I need some push forward.

The clone() method is your friend if you want to copy shapes.
You can read through the docs at svgjs.com to learn more.

For merging: No, that is not possible with svg.js albeit not impossible in general.
Its just that nobody requested this feature until now or nobody had the time to put their brain capacity into it to solve it.
There is a chance, that it gets considered, when you open a new issue and request that feature.
There is one problem with your idea though

// a line
canvas.line(0, 0, 200, 0)
<line x1="0" y1="0" x2="200", y2="0">

// an arc
canvas.path('M 200 0 A 100 100 0 0 200 200')
<path d="M 200 0 A 100 100 0 0 200 200">

// resulting path
canvas.path('M0 0 200 0 A 100 100 0 0 200 200')
<path d="M0 0 200 0 A 100 100 0 0 200 200">

// rotating the path
canvas.path('M0 0 200 0 A 100 100 0 0 200 200').rotate(90, 200, 200)
<path d="M0 0 200 0 A 100 100 0 0 200 200" transform="matrix(....)">

As you can see, rotating your path does not change the values of the d-attr. Rotation is a transformation which is done with the transform attribut. So you cannot easily merge these 2 paths together. Instead you first have to get rid of the transformation and apply it to every point directly. Then you can merge.
This ofc is again possible but maybe not something someone implemented already.
It would make a cool plugin, though...

Answering my own question if someone one day needed this.

First of all the SVG.js and its kinds do not work with geometry they work with SVG. Learn SVG first than decide whether do you need them or not. In my case, Vue will do work simpler.

As for others:

Duplicating - all that the SVG provides in my case mostly <use>, but be careful with styles they are unchangeable.

Arrays - no such thing not as in a CG graphics editor, you should program them yourself. As I sad SVG.js only help you with SVG not with geometry

Merging - theoretically possible but there is no out of the box solution.