Skip builds when changing docs only?

[native-api]

Duplicate of

How to skip jobs based on the files changed in a subdirectory?

I am working at a company who use the monorepo pattern to store their code. Each sub project has its own test and deploy job so every push to this repo will blindly test and deploy all the projects. In order to reduce build times I would like to only build the projects within which files have changed. Sadly this does not seem to be possible using the Travis conditional syntax as that only works on prefixed meta data (such as the branch name etc). Ideally I would be able to run a script, as earl…