Add Element to Sharepoint List from Custom Visual

[CristinaD]

Hi,

I'm trying to create a custom visual that use the SpRestLib to add/edit/remove rows in a sharepoint list. I have written the javascript and imported the library and it seems that there are no errors in the code. 
When I run it to test it I recived an error of the networ saying: 
Access to XMLHttpRequest at https://app.powerbi.com/_api/contextinfo' from origin 'null' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: The 'Access-Control-Allow-Origin' header has a value 'https://teams.powerbi.com' that is not equal to the supplied origin.

I have tried to do it from a sharepoint aspx page and everything works fine there since it is on the same platform and I have no problem with CORS. I have always had a hard time understanding calls to apis, headers, security, etc. Can anyone help me to solve the issue?

Thanks in advance