This is a Sony TV remote control running entirely on a web page and a Progressive Web Application (PWA). As such, this application can be used online, installed locally, or installed as a web extension. I wrote this application because my wife is the master of the TV controller, so I needed a second controller for the occasional evil games I could play fighting over a TV program.
Only Sony Bravia TVs are capable of using this web page because they include APIs for use by home automation specialists to connect with their home automation systems.
Sony Bravia TVs (2016 or later, some earlier ones too) support IRCC control (infrared-like-control-commands). These can be sent to the TV over HTTP using a POST request. This request is also secured with a Pre-Shared key (PSK) that must be provided in the POST request header. Cross-Origin Resource Sharing (CORS) headers are also correctly handled in the JavaScript.