Installing module dependencies

[karneaud]

How are 3rd party dependencies for modules handled? Do I install them into the root of the project or Can I install them root of module?

[karneaud]

Thus,... are they handled by adding them to the module.json as you would a composer.json file?

[pipegris]

AFIK if you add it to the root project, it would be available in the whole system (given you import it with the appropiate namespace). But if you need a separate composer.json file per module, I used this plugin for that, don't know if someone knows a better alternative.
https://github.com/wikimedia/composer-merge-plugin
Cheers!