Debugger always slow & js error line usually wrong

Developer Tools
#1

So I have to best honest. I find the firefox developer tools to really be unreliable.

When you have a JS error it will display the error in the console. I find that this error location is always nearly the wrong line. What I mean by that on the right hand side it has a blue link, if you click on it, the link takes you to where the error supposedly is. Many times it will just take me to the top of HTML, or it will show some error in up in the chain so far that it is showing a library file.

On the flip side if I want to try and debug and step through issues, the debugger is so slow it is locking up my browser and takes a long time for things to happen. The computer I am doing the debugging on has like 32 gigs of ram and is an i7.

I like Firefox and don’t want to be so negative and complain, but this is really not helping me do my work.

#2

Thank you @goddard for the reports.

Many times it will just take me to the top of HTML, or it will show some error in up in the chain so far that it is showing a library file.

A major bugfix for source locations landed in Nightly, 79. Could you help us by trying to reproduce your issue in Nightly (or if its too random, just using Nightly for a debugging session).

On the flip side if I want to try and debug and step through issues, the debugger is so slow it is locking up my browser and takes a long time for things to happen.

For the stepping performance, a lot improved here as well (across 77-79) so I want to make sure you are using at least DevEdition. If you hit a slow issue, could you record a performance profile with profiler.firefox.com while it happens and share it here or in a bug?