aks- / error-reporting-demo Goto Github PK

This repo demonstrates various classes of Errors that can happen in browser which your instrumentation tool might not be able to catch. Mostly RUM libraries can hook into console.error, unhandled promises etc and report them. But I think OOM and locking event loop has no hooks to hook into. Open your browser console to see the following errors being reported.

CSP is a policy specification, and as part of that it has a reporting clause to detect failures server side. Meaning you would have to have some endpoint where browser can report these errors. Look at server.js to see how header is set and csp.html triggers this error by implementing inline script. Open the console in dev tools and you would see something like this

Refused to execute inline script because it violates the following Content Security Policy directive: "default-src 'self'". Either the 'unsafe-inline' keyword, a hash ('sha256-/D1WJBtVfpl0d3pZavHFL3RT+RwE/D7PmYp0sUH5sOs='), or a nonce ('nonce-...') is required to enable inline execution. Note also that 'script-src' was not explicitly set, so 'default-src' is used as a fallback.

You can lock the event loop by doing following, the question is can the RUM tool detect this somehow? it can happen on button click or something else can trigger it

	function lockEventLoop() {
		while (true) {}
	}
	lockEventLoop();

Go to locking-the-event-loop to check out the code

I have added the following script but this is not efficient but eventually it would report to console in dev tools. Following is the code I am trying to run to do so

    const array = [];
    function outOfMemory() {
      setTimeout(() => {
        array.push(new Array(1000000).join("x"));
        outOfMemory();
      }, 0);
    }
    outOfMemory();

Go to out-of-memory to see this in action

Git clone and run npm start, click around

npm install
npm start