Retrieving list data from multiple sub-sites using same site content type with JavaScript

Dear all,

I'm running a SharePoint site for projects where every project is created as a sub-site with a number of lists. Each sub-site has a list with one list item including the most important project data. This list is using a Site Content Type. I'd like to pull the data from all those lists and write it to one list on the parent site, e.g. by a weekly run of a workflow or manually.

Can this task be done by using JavaScript, Rest API, etc.? Has anybody done something similar?

Thanks for your tips.