How to construct a WebSocket URI relative to the page URI?
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://example.com:8000/path
to
ws://example.com:8000/path/to/ws
wss://example.com:8000/path/to/ws
What I'm doing currently is replace the first 4 letters "http" by "ws", and append "/to/ws" to it. Is there any better way for that?
Solution 1:
If your Web server has support for WebSockets (or a WebSocket handler module) then you can use the same host and port and just change the scheme like you are showing. There are many options for running a Web server and Websocket server/module together.
I would suggest that you look at the individual pieces of the window.location global and join them back together instead of doing blind string substitution.
var loc = window.location, new_uri;
if (loc.protocol === "https:") {
new_uri = "wss:";
} else {
new_uri = "ws:";
}
new_uri += "//" + loc.host;
new_uri += loc.pathname + "/to/ws";
Note that some web servers (i.e. Jetty based ones) currently use the path (rather than the upgrade header) to determine whether a specific request should be passed on to the WebSocket handler. So you may be limited in whether you can transform the path in the way you want.
Solution 2:
Here is my version which adds the tcp port in case it's not 80 or 443:
function url(s) {
var l = window.location;
return ((l.protocol === "https:") ? "wss://" : "ws://") + l.hostname + (((l.port != 80) && (l.port != 443)) ? ":" + l.port : "") + l.pathname + s;
}
Edit 1: Improved version as by suggestion of @kanaka :
function url(s) {
var l = window.location;
return ((l.protocol === "https:") ? "wss://" : "ws://") + l.host + l.pathname + s;
}
Edit 2: Nowadays I create the WebSocket
this:
var s = new WebSocket(((window.location.protocol === "https:") ? "wss://" : "ws://") + window.location.host + "/ws");
Solution 3:
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