improve url builder for Discord Activities

package.json

@@ -1,6 +1,6 @@
 {
   "name": "colyseus.js",
-  "version": "0.15.25",
+  "version": "0.15.26",
   "description": "Colyseus Multiplayer SDK for JavaScript/TypeScript",
   "author": "Endel Dreyer",
   "license": "MIT",

src/3rd_party/discord.ts

@@ -3,22 +3,46 @@
  * https://github.com/colyseus/colyseus/issues/707
  *
  * All URLs must go through the local proxy from
- * https://<app_id>.discordsays.com/<backend>/...
+ * https://<app_id>.discordsays.com/.proxy/<mapped_url>/...
  *
- * You must configure your URL Mappings with:
- * - /colyseus/{subdomain} -> {subdomain}.colyseus.cloud
+ * URL Mapping Examples:
  *
- * Example:
- *  const client = new Client("https://xxxx.colyseus.cloud");
+ * 1. Using Colyseus Cloud:
+ *   - /colyseus/{subdomain} -> {subdomain}.colyseus.cloud
+ *
+ *   Example:
+ *     const client = new Client("https://xxxx.colyseus.cloud");
+ *
+ * -------------------------------------------------------------
+ *
+ * 2. Using `cloudflared` tunnel:
+ *   - /colyseus/ -> <your-cloudflared-url>.trycloudflare.com
+ *
+ *   Example:
+ *     const client = new Client("https://<your-cloudflared-url>.trycloudflare.com");
+ *
+ * -------------------------------------------------------------
+ *
+ * 3. Providing a manual /.proxy/your-mapping:
+ *   - /your-mapping/ -> your-endpoint.com
+ *
+ *   Example:
+ *     const client = new Client("/.proxy/your-mapping");
  *
  */
- export function discordURLBuilder (url: URL): string {
+export function discordURLBuilder (url: URL): string {
     const localHostname = window?.location?.hostname || "localhost";
 
     const remoteHostnameSplitted = url.hostname.split('.');
-    const subdomain = (remoteHostnameSplitted.length > 2)
+    const subdomain = (
+        !url.hostname.includes("trycloudflare.com") && // ignore cloudflared subdomains
+        !url.hostname.includes("discordsays.com") &&  // ignore discordsays.com subdomains
+        remoteHostnameSplitted.length > 2
+    )
         ? `/${remoteHostnameSplitted[0]}`
         : '';
 
-    return `${url.protocol}//${localHostname}/colyseus${subdomain}${url.pathname}${url.search}`;
- }
+    return (url.pathname.startsWith("/.proxy"))
+        ? `${url.protocol}//${localHostname}${subdomain}${url.pathname}${url.search}`
+        : `${url.protocol}//${localHostname}/.proxy/colyseus${subdomain}${url.pathname}${url.search}`;
+}