How to construct a WebSocket URI relative to the page URI?

Question

I want to construct a WebSocket URI relative to the page URI at the browser side. Say, in my case convert HTTP URIs like

http://example.com:8000/path
https:/         


        

Answer 1

Using the Window.URL API - https://developer.mozilla.org/en-US/docs/Web/API/Window/URL

Works with http(s), ports etc.

var url = new URL('/path/to/websocket', window.location.href);

url.protocol = url.protocol.replace('http', 'ws');

url.href // => ws://www.example.com:9999/path/to/websocket