Detect change of readyState with SSE

Question

I am using HTML5 Server-Sent events:

SSEUpdate = new EventSource("update.php");

I want to detect when SSEUpdate.readyState changes. I've tried .onerror, but when I use console.log(SSEUpdate.readyState), I always get 0. I want to run my function when readyState changes to 2.

Answer 1

I ended up using a polling solution:

var SSECheck = setInterval(function() {
    if (SSEUpdate.readyState == 2) {
        clearInterval(SSECheck);
        // call to fn to restart sse
    }
}, 500);

Takes up to 0.5s to capture, but it does the job.