How many package.json file should a full-stack app have?

When initating a basic back-end application in node.js (in my case I'm using typescript) one would usually have package.json in the root of their project.

When initating a Angular-cli project one would have a package.json the angular-cli root folder.

When working on my full stack project I used Angular-cli for the front-end, and my question is this, should I merge the the package.json files, or should I leave it be? (this question could be expanded by saying That I'd like to add NativeScript in the future which will add another package.json to the deal)

Thanks in advance!

via Lopierdis