How to export custom elements?

Hi,

after following the example custom-elements I can not save the new components so that in the future I can import the saved files again and continue from where I left off.

I saw custom-meta-model, but that still did not help me.

does anyone know of a project that after adding custom components can save, even if separated, as much as i would prefer in the same file, the new custom components?
a link to this project, if it is available in github, it will help me a lot, or if possible guide me to get it resolved, thanks for all the help.

short version: I have added the new components and everything is alright, but I can not export the new components in the xml file.

here is the code to export (I am using react, but there will not be much difference in implementation):

saveFile = (e) => {
      var downloadURL = "";
      this.modeler.saveXML({ format: true }, function(err, xml) {
        downloadURL = 'data:application/bpmn20-xml;charset=UTF-8,' + encodeURIComponent(xml);
      });
      this.setState ({downloadURL: downloadURL});
    }

I want to know the update on this .Kindly do let me know as this is urgent

This seems to be a duplicate of this topic, right? I think you can find help there.