I have a single process node.js application, which I wish to debug with Intellij IDEA 11 32 bits (node.js is 32 bits too).
So, I place an initial breakpoint and run. The debugger stops at the breakpoint, but then it refuses to do any of the following:
step into
go to another breakpoint
pause execution
When I step into, it seems just to run, without stepping through the code. Once running, it ignores any subsequent breakpoints and does not break when I press the pause button.
This issue drives me crazy.
Any ideas on how should I troubleshoot it?
EDIT
More info. After IDEA breaks on the first breakpoint (the only successful time) I try to inspect the variables and am unable to see any. IDEA is stuck on "Collecting data..." The watch window does not work too.
EDIT2
Justed posted an issue to their bug tracking system - http://youtrack.jetbrains.com/issue/IDEA-112925
I've been noticing that IntelliJ's node.js debugger kinda sucks. It's death by 1000 cuts. I love IntelliJ to death, its such a nice IDE. But for node, the debugger has a million different scenarios where breakpoints don't work properly, and another million where it doesn't properly give you access to the in-scope variable values, and another million where it doesn't step properly...
I'm gonna hafta try looking for another tool..
UPDATE 2014-01-13: I've been using IntelliJ's debugger for a while now (having found no other good tool). It seems some of the problems with it are problems with node or v8 itself. Most of the problems I was having have either actually been solved by newer versions of IntelliJ, or by using this workaround:
1. create a file called proxyDebug.js
2. put the following content in it:
require('path/to/the/script/you/want/to/debug.js')
3. point your debugger to that file
Apparently the node.js debugging hooks go buggy at the entrypoint script, so by creating this proxy entrypoint that we don't care at all about, there won't be any weird bugs caused by that in the scripts you do care about. The bugs this workaround fixed were missed breakpoints, predefined variables (exports, module, process, etc) being inaccessible by the debugger, and one or two other things I can't remember.
Last WebStorm version I tried (7.0.3) actually takes ages in collecting data but eventually works. If it seems stuck to you, try to leave it for a minute
Related
Newbie question here, it seems... I'm losing my mind. Why is this so hard? I've been programming other languages for years, but I'm relatively new to node and JS. I've read and watched as much as I can find official and unofficial on the web about this and it's either years old or significantly different from my situation, so not very helpful.
I'd really, really appreciate anyone who can understand my (pretty simple, I would have thought!?) specific case and help me get this set up to just work. Possible?
macOS 10.15.6 Catalina.
As I understand it, node comes with the OS. It's Node.js 12.8.1
VS Code 1.48.2
I create a new file, name it abcd.js. VS Code figures out it's javascript. I add some code - read a file of JSON from the disk, make some changes, console.log some stuff (appears under the Output tab). I run it.* All good and works.
Now... Run menu > "Start Debugging". Or, There's a Run/Debug icon in the sidebar that shows a "Run and Debug" button which I click on. Both of those ask me for an environment - I choose Node.js, and the Debug console outputs this:
/usr/local/bin/node path/to/my/file.js
Debugger listening on ws://127.0.0.1:56430/30b0c2aa-278b-4540-94c4-825d30b94f57
For help see https://nodejs.org/en/docs/inspector
And that's it. I have breakpoints, but it doesn't stop on them. Something happens (too quick to see what it is). I don't think it's actually running my code because nothing new shows up under the Output tab.
There's also a note in that sidebar saying "To customize Run and Debug create a launch.json file." I've experimented with that as much as I can, but nothing I do seems to help.
I've been programming for years. I'm used to other languages and IDEs (eg. C, Java, AppleScript, Swift, others), where you open the IDE, write some code, hit run (or debug), it may or may not build a target (depending on the language and environment), but then it runs the code (opens the target app, or runs in the IDE, and allows you to step through the code, breakpoints, etc. in the IDE if debugging). Is JS/node programming radically different from this somehow?
*One theory:
I'm not doing this through any terminal or any browser. Maybe that's the problem...? At some point I installed a "Code Runner" plugin that I believe is what is running my code. It was a while ago, but if I recall correctly maybe I turned to that because I was looking for the experience I've described above, and this plugin gave me that where the "normal" node setup process didn't? Perhaps my problem is that that plugin simplifies RUNNING js scripts so much that my issues with DEBUGGING exist because that plugin allows me to bypass other usual complications with running JS/Node scripts (but doesn't have any debugging functionality of its own)?
My thanks to #ippi for his/her comment with a gif video. Not sure if the following really answers my question, but I'm posting it in case it helps anyone else.
I took some time to clean up my Mac a little, and I completely uninstall VSCode, all its extensions and supporting files and started again.
I re-installed Code from scratch, didn't add any extensions, and then tried what #ippi's video showed.
It still didn't work - I got more or less the same output as in my post, and I'm not sure if it was running the code or not.
I had an urgent deadline to meet so didn't come back to it till now - two days later - and now, it's working.
A couple of things changed in that time though I really don't know what fixed this, if it was either of those or anything else. The two changes I can remember that I've done the last two days are:
Despite my post saying my node was 12.8.1, sometime in the last couple of days it turned into 8.something. I updated it to the latest v12.8.3, and
to meet that deadline I used node inspect myfile.js in Terminal for a bit.
The inspect (mostly) worked to meet my deadline, but still a hassle compared to what's shown in #ippi's video. I definitely wanted to get it working that way.
So… updating node fixed it? Running it in the terminal for a bit fixed it? Something else? I'm at a loss to know what did it. But it's working now.
Thanks again to #ippi for that. It pointed me in a good direction at least - to clean up my install a bit, if nothing else.
Maybe this will help someone else sometime in the future.
It seems the ultimate answer is:
It should just work out of the box (possibly subject to updating node to its latest). If it doesn't then:
The issue most likely isn't that you have to do any fancy configuring or whatnot to make it work.
Instead, most likely something is wrong with your installation and/or OS and you should explore that.
#ippi's video attached in case his/her link ever breaks:
I have more general question on how you usually approach on debugging page with tons of javascript (mostly third-party add-ons) and event watchers to discover the problematic line, which in my case causes the Chrome to crash or Firefox to freeze?
I have a landing page with many external dependencies: the usual suspects like jquery and bootstrap, but also many add-ons like sliders, re-size watchers. When I re-size there is a micro-freeze on Firefox and a crash on Chrome. This is from any block of code (some watchers most probably).
After page crashes I lose all of my dev tool data. Firebug doesn't have the timing control over scripts execution, and if I start with breakpoints I have to put dozens.
How you usually proceeding to identify the script that causes the problem and further more the block of code?
If I start with breakpoints I have to put dozens.
I used to have this problem a lot back with Internet Explorer 4/5. Those browsers made such poor use of memory that almost any significant error wold result in the browser crashing. And even before it did, the browser debugging tools were far, far worse than the Chrome ones. So what did I do? Sadly, debugger and console.log.
You must have some idea, or ideas, as to where the problem lies, so just start at wherever you are certain your code is working and add a console.log (if you can still see the logs up to the crash) or a debugger (if you can't) to every point along the way to the crash. Eventually you won't make it to one of your debugging statements, and then you'll know that the problem is in-between that statement and the previous one.
It's a really lame way to debug, I know, and as you said you will have to add a lot of debugging statements, but sometimes it's all you have.
The project I'm working on involves a "planning" screen, which is entirely made with backbone.js (the other pages of the app are not).
My issue is that from times to times, chrome freezes and the web view stop responding to any interaction. Sometimes, I can manage to quit chrome itself, but usually the controls does not answer either.
I'm pretty convinced this is related to the js code. It seems to me that when a script takes too much time, or loops indefinitely, Chrome can detect this and interrupt the script. However, since this is not the case, I'm thinking that too many js objects stay in memory.
Whatever the cause is, I would like to know which chrome dev tools can help me here. While I'm not a beginner in js, asides setting breakpoints and calling console.log, I have no idea how to debug JS apps. I'm not opposed to use another browser if the dev tools are more suited.
Thanks a lot for your time !
FTR : This is a rails 3.2.8 app, using mongodb, & Backbone.js 0.9.2. The js code is written in coffeescript. This issue happened on my macbook air 2012 running mountain lion, as well as on the client machine which runs on windows 7. The issue appeared at least on chrome 22 & 23.
Using the Javascript CPU profiler, I was able to find the group of functions that seems to be responsible for the freezing.
I'm still open to any advice/ressource on debugging javascript code.
Make a console.log in the loop and check if its the same point freezing on all chrome versions. There is a limit see Browser Javascript Stack size limit.
Maybe add some code? Because there could be some memory leaks especially with event handlers!
What I would do is the long and weary approach to getting your hands dirty with console.log. --- in this case.
In your case, and THX for the hint by the way (finding the offender with the CPU profiler, I'll try that next time round), I guess the offenders might be some functions "callbacking" themselves .. probably via some sort of event-handling/bubbling/callback-combination.
What happens then usually is that it just doesn't recognize the endless-loop, because the callback-stack is kinda "broken". Therefor it will never throw a browser-error.
If you have any luck, it doesn't kill the browser quick enough to kill the console. I did have that at times, the console killed (remaining silent), the coffeescript files not even loaded in the debugger (I use a JIT-coffee-to-js-translator as in JS-MVC) ... the page frozen or not doing anything ...
So, if indeed you are lucky and the debugger spits out your console.logs you can thereby guess where your unwanted loop is hiding. Just by looking at the repeated order of the output statements.
of course you know you can set breakpoints right? even conditional breakpoints
I'm currently struggling a bit untangling a similar sounding loop - i guess in case of emergency some alert() calls in your code would at least slow the loop down
or maybe some wait calls (bad idea)
my loop is running so fast I loose my console log!
After an hour or two of heavy use on the site I'm developing, Firebug develops the following problems:
Breakpoints get glitchy -- it becomes difficult to add/remove breakpoints. Sometimes I click on a line multiple times, see nothing, move to the console tab and back, and then see my breakpoints again.
Console stops logging xhr's, or stops logging debug statements.
Script files become non-viewable.
I'm working with a javascript file which is quite large (over 10k lines). I don't think this is a memory leak issue with my own code. I'm refreshing the page all the time. Looks like an issue on the Firebug side. Is my logic sound? Is there anything I can do to get firebug to behave better? Or do I just need to restart firefox every hour?
Keep in mind Firefox while wonderful has always had many issues with handling memory. You should take a look at your task manager to see Firefox's memory footprint. Additionally I'd break up that JS file if you could into smaller chunks (for many reasons aside of this as well) to be better readable and work with the segments. Finally turn off plugins your not using or that may conflict with Friebug if your not using them.
I spent hours using Firebug without restart Firefox and never crashed, try a clean profile, install on it only Firebug and check if all works fine.
I use a separated development profile with Firebug and other dev oriented extensions installed.
How to configure a profile is described in many sites, on my wiki you find a brief description
i have similar problems! i think it is partially to do with the massive JS files. I just re-start firefox every once and a while. no big deal.
I have a page that has a byzantine amount of JavaScript code running. In Internet Explorer only, and only version 8, I get a long-script warning that I can reliably reproduce. I suspect it is event handlers triggering themselves in an infinite loop.
The developer tools are limping horribly under the weight of the script running, but I do seem to be able to get the log to tell me what line of script it was executing when I aborted, but it is inevitably some of the deep plumbing of the ExtJS code we use, and I can't tell where it is in my stack of code.
A way of seeing the call stack would work, but preferably I'd like to be able to just break into the debugger when I get the long script warning so I can just step through the stack.
There is a similar question posted, but the answers given were for a not-the-right-tool, or the not terribly helpful advice to eliminate half my code at a time on a binary hunt for the infinite loop. If my code were simple enough that I could do that, it probably wouldn't have gotten the infinite loop in the first place. If I could reproduce the problem in Firebug, I'd probably be a lot happier too.
Here is what I would do:
Go to http://www.microsoft.com/whdc/devtools/debugging/default.mspx and install the Debugging Tools for Windows. You want to run WinDBG when this is installed.
Follow the steps outlined at http://www.microsoft.com/whdc/devtools/debugging/debugstart.mspx#a to setup the symbol server connection and have the symbols automatically downloaded to your local drive (c:\websymbols -- or whatever).
Run IEXPLORE.EXE under WinDBG. The help file should give you assistance in doing this if necessary. You need a couple of commands once you get Internet Explorer running and such. First, go ahead and get that large script going.
Break into the debugger (CTRL-SCROLLLOCK to break).
a. Do a LN to "list nearest" to get the DLL files that are loaded. Hopefully, you'll have JSCRIPT.DLL loaded in memory.
b. Type .reload /f to force the reloading of all of the symbols. This will take a while. Now, after this is done, type LN again and you should see that the proper JSCRIPT.PDB has been downloaded to your system in the symbols directory you setup earlier.
Depending on what you want to do, you may need to restart the debugger, but you can do this: After the initial break on WINDBG load, you can type "sxe ld jscript.dll" and it will break when jscript.dll loads.
This is the tricky part, because once this loads, you don't have the code for jscript.dll, but you have the proper symbols (if they are not loaded, then reload them with .reload /f). You can view the functions available by typing "x!jscript" and you'll get a full list of all of the functions and variables.
Pick one, set a break point, and then you should be able to track what is happening to your script.
If nothing else is accomplished, by using the .reload /f process, you can get the appropriate jscript.pdb files loaded on your system. It's possible you could use these in conjunction with Visual Studio to do additional debugging in that manner, but I'm not so sure how well that will work.
I've run in to this before and have had some luck with enabling the developer tools along with Visual Studio. When an error is encountered the page loading is halted, and I could then load up Visual Studio to see the specific line causing the trouble.
This site has some information on using Visual Studio along with the Internet Explorer debugger: Using Visual Studio to Debug JavaScript in IE