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

Answer 2

In typescript:

export class WebsocketUtils {

    public static websocketUrlByPath(path) {
        return this.websocketProtocolByLocation() +
            window.location.hostname +
            this.websocketPortWithColonByLocation() +
            window.location.pathname +
            path;
    }

    private static websocketProtocolByLocation() {
        return window.location.protocol === "https:" ? "wss://" : "ws://";
    }

    private static websocketPortWithColonByLocation() {
        const defaultPort = window.location.protocol === "https:" ? "443" : "80";
        if (window.location.port !== defaultPort) {
            return ":" + window.location.port;
        } else {
            return "";
        }
    }
}

Usage:

alert(WebsocketUtils.websocketUrlByPath("/websocket"));