author: Krasimir Tsonev

Hi there, I'm . Senior front-end engineer with over 13 years of experience. I write, speak and occasionally code stuff. Follow me on Twitter, GitHub, Facebook or LinkedIn

Chrome extension: debugging dev tools tab or how to make console.log

It's really interesting to work on an extension for Chrome. However, sometimes it's a little bit difficult to debug. Especially when you work on a dev tools add-on (i.e. a new tab).
As you may guess
doesn't work in the code of your new dev tools tab. Instead of that I used alert. If the thing which you want to see is something primitive, it's easy. Just pass it to alert function. If not you can use
Anyway, using alert is not the coolest thing, mainly because you have to comment those lines or manually remove them. Also, it's a little bit irritating from user experience point of view. What I did is to send a message to the background page. That's in one of my dev tools scripts:
	// console.log in the background page
	var bglog = function(obj) {
		if(chrome && chrome.runtime) {
			chrome.runtime.sendMessage({type: "bglog", obj: obj});
Then in the background page:
	var onMessageListener = function(message, sender, sendResponse) {
	    switch(message.type) {
	        case "bglog":
	    return true;
Really simple, but the background script could be easily inspected. Open chrome://extensions, find your extension and you will see:
Inspect views: _generated_background_page.html
Click on that link and a new dev tools will be opened. The console there accepts logs from the background script.
If you enjoy this post, share it on Twitter, Facebook or LinkedIn. Or maybe comment below: