Injecting Javascript with Sharepoint Framework Extensions (Preview) - Azure Application Insights

First than all, remember that this feature is in preview, therefore the code I show here might change in the future, keep an eye on the official documentation in case you want to compile this for future builds of Sharepoint Framework Extensions.

On the Getting Started page from the official documentation, it shows how to add a div in the header placeholder and footer placeholder, however if you try to add javascript code there, it wont work, so what I tried first was the following, the code had no exceptions but it wasnt executed, and I had no STATS on the App Insights account, so my first try according to the documentation was this.

Official documentation:
https://dev.office.com/sharepoint/docs/spfx/extensions/overview-extensions

See full post here: http://luisevalencia.com/2017/06/08/injecting-javascript-with-sharepoint-framework-extensions-preview-azure-application-insights/