Adding custom Nodes


I want to add a Node with a custom shader (as you can see at picture), but I’m not sure how to do it.

There is any way (doc) to add custom nodes?

In code I think should look like this:

let material = new Nodes.MeshStandardNodeMaterial();
material.colorNode = new Nodes.MyCustomShader(
    new Nodes.TextureNode( texture ),
    new Nodes.FloatNode( 0.5 )

Am I wrong trying to use Nodes this way?