How to debug web workers

I have been working with web workers in HTML 5 and am looking for ways to debug them. Ideally something like the firebug or chrome debuggers. Does anyone have any good solution to this. with no access to the console or DOM its kind of hard to debug iffy code

Dev Channel version of Chrome supports debugging of workers by injecting fake workers implementation that simulates workers using an iframe within worker's client page. You will need to navigate to Scripts pane and tick Debug checkbox on Workers sidebar on the right, then reload the page. The worker script will then appear in the list of page scripts. This simulation has certain limitations, though -- since worker script will run in the client page thread, any long-running operations in worker will freeze the browser UI.

As a fast solution on the missing console.log, you can just use throw JSON.stringify({data:data})

The WebWorker can be debug just like a normal webpage. Chrome provides debugging dev-tools for WebWorkers at: chrome://inspect/#workers

Locate the desired running webworker and click "inspect". A separate dev-tool window will open dedicated to that webworker. The official instructions is worth checking.

Starting with Chrome 65, you can now simply use the "step-in" function of the debugger:

For more details, see their release note.