Firefox - Disable 'debugger' keywords

Question

How do I tell Firefox not to stop if it sees a debugger keyword?

I need to avoid a continuous debugger loop in case the website uses debugging protection generating debugger statements on the fly using timers.

Here is an example. In case you open the debugging console the script will throw tons of debugger statements, which will block you from normal debugging work.

An example website is http://www.avito.ru - the biggest classified site in Russia. Open it and then open the debugger console and it will be immediately stop at the debugger keyword in generated script.

(function(x/**/) {
    (function(f){
        (function a(){
            try {
                function b(i) {
                    if(
                        (''+(i/i)).length !== 1 ||
                        i % 20 === 0
                    ) {
                        (function(){}).constructor('debugger')();
                    } else {
                        debugger;
                    }

                    b(++i);
                }

                b(0);
            } catch(e) {
                f.setTimeout(a, x)
            }
        })()
    })(document.body.appendChild(document.createElement('frame')).contentWindow);
});

Solution 1

In the current version of Firefox at writing this answer (ver 63.0.3), in the Developer Tools, the Debugger section, there's an icon with the tooltip "Skip all pausing" or "Deactivate breakpoints". When enabled it seems to disable stopping at any debugger instruction.

Solution 2

Obviously the page tries to avoid people from debugging their JavaScript code with that construct.

Debugging in Firebug

Firebug allows to set disabled breakpoints on the debugger statements. Because the page generates a variable call stack depth, you'll need to set those disabled breakpoints for all of them to be able to debug the JavaScript properly. Unfortunately, Firebug seems to be buggy when it comes to set those breakpoints.

Furthermore, Firebug doesn't have an option to ignore all debugger statements.

So, if you don't need to debug JavaScript but only HTML, CSS, network requests, etc., you can simply disable the Script panel to avoid these annoying debugger halts. To do so, right-click the Script tab and click on Enable within the opening menu.

Note: Because Firebug development is discontinued, it's useless to file an enhancement request for it.

Debugging in Firefox DevTools

Unfortunately, the Firefox DevTools currently don't allow to avoid halting on debugger statements. So you have to wait until bug 1300934 (which mentions the same website as an example), bug 925269 and/or issue 828 are fixed.

Furthermore there is no way to disable the Debugger panel completely, which is filed as bug 1247198.

Solution 3

if you use Greasemonkey you can rewrite setTimeout/setInterval function to disable the script

unsafeWindow.setTimeout = function () {};

Solution 4

Chrome

in chrome you can edit the breakpoint and put a condition that is always false, it won't hit the debugger anymore

another option is to use "never pause here"

Firefox

for firefox, you can blackbox the script that you don't want to be hit by the breakpoint. for me it causes to hang the firefox. but when you restart the browser. then it's okay,

View more solutions

Comments

[Sebastian Zartner]

As you didn't mention which tool you're using, I've added the 'firebug' and 'firefox-developer-tools' flags.

[Sebastian Zartner]

For reference, the same question was asked in the Firebug discussion group, providing the website www.avito.ru as example.

[user201202]

Sebastian, that was me seeking for help in there as well :)

[Sebastian Zartner]

I thought so :-), though in your question here you didn't include the website as example, so I thought I'll mention it in a comment. You may still adjust your question to include the link.

[T.J. Crowder]

Firebug is, of course, open source (as is Firefox). So it may be possible to modify it to add the desired feature and send a pull request.

[Sebastian Zartner]

Correct, though as noted, Firebug is discontinued and stops working once multi-process Firefox is enabled. Also the Firefox DevTools are open source, so it might be better to provide a patch for them instead.

[T.J. Crowder]

Sorry, I meant "modify either of them" rather than specifically Firebug.

[user201202]

So basically there is only one option - try to implement this feature for firefox dev tools and get it approved ...

[Sebastian Zartner]

Correct. As the main work on the debugger seems to be on GitHub now, issue 828 seems the right place to do that.

[Tobia]

This is why modern interfaces suck. In the old days, that would have been a menu item in a "Debug" top level menu.

[Yeti]

This did not work for me, debugger still halts on debugger.

[Ben Philipp]

This, of course, will prevent all timeout timers in the page window scope from working

[TheSola10]

> there is no way to disable the Debugger panel completely Wouldn't devtools.debugger.enabled=false do the trick in about:config?

[Sebastian Zartner]

This preference suggests that you can disable the Debugger, though from my tests it doesn't have any effect. The Debugger panel is still there and works the same with this preference enabled or disabled. And this observation is confirmed by looking at the code, which shows that the preference is never read within the debugger code.