In outlook add-ins make any API request for authentication any third party API getting cors error , why this problem occurs ,

what is the reason for this issue , reason for this issue frond end side or API side

example : if i make any request to microsoft API or salsforce authentication getting cors error ,

For any other request in microsoft office with access token , it is working fine ,only getting this error any authentication request

Note : This issue comes from local environment and add-in developed using javascript