Provide script injection on tenant level
This idea is somewhat similar to what Marc Anderson posted here: https://sharepoint.uservoice.com/forums/329220-sharepoint-dev-platform/suggestions/10533423-add-a-load-javascript-link-to-master-page-settin. But instead of limiting this capability to a site collection scope, it would be great to have an equal option on tenant level as well.
Simply provide the option to set some URLs to be loaded as additional JavaScripts on each page within the SharePoint tenant. The simplest use case would be to enable analytics like Azure Application Insights or Google Analytics. Each URL gets loaded within the script manager of a SharePoint page and the script then can take care of loading other resources when needed.
Yes, we can now do somewhat the same with custom actions within an add-in, but that a lot of effort to get just one <script> tag within the page source.
Jasper Siegmund
shared this idea
As part of the future roadmap for the SharePoint Framework, we are looking into doing something similar as explained in here. Stay tuned, more public information hopefully soon.