How to deal with Cross Origin issue with nodejs / sse module

How do I handle on the server side the cross origin issue which triggers on the client the following error?

Uncaught Error: SECURITY_ERR: DOM Exception 18

Thanks.

[einaros]

It'll have to be extended to support the passing of the Access-Control-Allow-Origin header. Should be a pretty quick fix.

That said I am not entirely sure about the state of CORS for SSE in browsers. When I last dug into it, the support was sketchy, but from a quick Google search it seems better now.

Thanks for the response. I am a bit new to nodejs and especially to npm modules management tool. I have installed the sse module through npm. This is where the module files has been placed:

/usr/share/npm/node_modules/sse/lib $ ls -l
total 8
1155 Aug 10 09:32 sseclient.js
1404 Aug 10 09:34 sse.js

I modified directly the code of sse.js by changing the handleRequest function when it writes the header:

SSE.prototype.handleRequest = function(req, res) {
req.socket.setNoDelay(true);
var isLegacy = req.headers['user-agent'] && (/^Opera[^\/]/9/).test(req.headers['user-agent']);
if (isLegacy) {
res.writeHead(200, {'Content-Type': 'text/x-dom-event-stream'});
}
else res.writeHead(200, {'Content-Type': 'text/event-stream',
'Access-Control-Allow-Origin' : ''});
console.log("{Setting the headers");
res.write(':ok\n\n');
this.emit('connection', new SSEClient(req, res, isLegacy));
}

However I don't see the log to console (to make sure it is actually executing this code) and of course the cross origin issue still shows up. So I am not sure if it is correct to modify the file directly installed on the node_modules/sse/lib directory or if the way I changed the code is not correct. Any suggestion ?

Thanks

I also did a locate of sse.js to see all the possible places where npm would place a module files:

locate sse.js
/home/diegosacc/.npm/sse/0.0.3/package/lib/sse.js
/usr/share/npm/node_modules/sse/lib/sse.js

so I went ahead to make the same changes on /home/diegosacc/.npm/sse/0.0.3/package/lib/sse.js but still I don't see the log "Setting Headers". This tell me the sse.js files I changed are not the one picked up at runtime.

[dman777]

Hi, looking to use this. Has this issue been resolved?

[capJavert]

I used patch-package to modify source of this package and add CORS header.

This will add wildcard CORS header (be aware that all origins will be allowed):

diff --git a/node_modules/sse/lib/sseclient.js b/node_modules/sse/lib/sseclient.js
index 06c2c5e..b918ba9 100644
--- a/node_modules/sse/lib/sseclient.js
+++ b/node_modules/sse/lib/sseclient.js
@@ -19,7 +19,8 @@ SSEClient.prototype.initialize = function() {
   this.res.writeHead(200, {
     'Content-Type': 'text/event-stream',
     'Cache-Control': 'no-cache, no-transform',
-    'Connection': 'keep-alive'
+    'Connection': 'keep-alive',
+    'Access-Control-Allow-Origin': '*'
   });
   this.res.write(':ok\n\n');
 };