javascript - visual - nodejs debug chrome




How do I debug Node.js applications? (20)

Node has its own built in GUI debugger as of version 6.3 (using Chrome's DevTools)

Simply pass the inspector flag and you'll be provided with a URL to the inspector:

node --inspect server.js

You can also break on the first line by passing --inspect-brk instead.

To open a Chrome window automatically, use the inspect-process module.

# install inspect-process globally
npm install -g inspect-process

# start the debugger with inspect
inspect script.js

How do I debug a Node.js server application?

Right now I'm mostly using alert debugging with print statements like this:

sys.puts(sys.inspect(someVariable));

There must be a better way to debug. I know that Google Chrome has a command-line debugger. Is this debugger available for Node.js as well?


Debugging

Profiling

  1. node --prof ./app.js
  2. node --prof-process ./the-generated-log-file

Heapdumps

Flamegraphs

Tracing

Logging

Libraries that output debugging information

Libraries that enhance stack trace information

Benchmarking

Other

Legacy

These use to work but are no longer maintained or no longer applicable to modern node versions.



Visual Studio Code has really nice Node.js debugging support. It is free, open source and cross-platform and runs on Linux, OS X and Windows.

You can even debug grunt and gulp tasks, should you need to...


Node.js Tools for Visual Studio 2012 or 2013 includes a debugger. The overview here states "Node.js Tools for Visual Studio includes complete support for debugging node apps.". Being new to Node.js, but having a background in .NET, I've found this add in to be a great way to debug Node.js applications.


IntelliJ works wonderfully for Node.js.

In addition, IntelliJ supports 'Code Assistance' well.


A lot of great answers here, but I'd like to add my view (based on how my approach evolved)

Debug Logs

Let's face it, we all love a good console.log('Uh oh, if you reached here, you better run.') and sometimes that works great, so if you're reticent to move too far away from it at least add some bling to your logs with Visionmedia's debug.

Interactive Debugging

As handy as console logging can be, to debug professionally you need to roll up your sleeves and get stuck in. Set breakpoints, step through your code, inspect scopes and variables to see what's causing that weird behaviour. As others have mentioned, node-inspector really is the bees-knees. It does everything you can do with the built-in debugger, but using that familiar Chrome DevTools interface. If, like me, you use Webstorm, then here is a handy guide to debugging from there.

Stack Traces

By default, we can't trace a series of operations across different cycles of the event loop (ticks). To get around this have a look at longjohn (but not in production!).

Memory Leaks

With Node.js we can have a server process expected to stay up for considerable time. What do you do if you think it has sprung some nasty leaks? Use heapdump and Chrome DevTools to compare some snapshots and see what's changing.


For some useful articles, check out

If you feel like watching a video(s) then

Whatever path you choose, just be sure you understand how you are debugging

It is a painful thing
To look at your own trouble and know
That you yourself and no one else has made it

Sophocles, Ajax


A quick-and-dirty way to debug small Node.js scripts with your favorite browser debugger would be to use browserify. Note that this approach doesn't work with any applications which require native I/O libraries, but it is good enough for most small scripts.

$ npm install -g browserify

Now move all your var x = requires('x') calls into a requires.js file and run:

$ browserify requires.js -s window -o bundle.js

(The downside here is that you either have to move or comment the requires in all your files.)

Include the bundle.js in an HTML file like so:

<script type="text/javascript" src="bundle.js"></script>

Now load the file in your browser and press F12 and viola: debug in browser.


I created a neat little tool called pry.js that can help you out.

Put a simple statement somewhere in your code, run your script normally and node will halt the current thread giving you access to all your variables and functions. View/edit/delete them at will!

pry = require('pryjs')

class FizzBuzz

  run: ->
    for i in [1..100]
      output = ''
      eval(pry.it) # magic
      output += "Fizz" if i % 3 is 0
      output += "Buzz" if i % 5 is 0
      console.log output || i

  bar: ->
    10

fizz = new FizzBuzz()
fizz.run()

I personally use JetBrains WebStorm as it's the only JavaScript IDE that I've found which is great for both frontend and backend JavaScript.

It works on multiple OS's and has Node.js debugging built-in (as well as a ton of other stuff](http://www.jetbrains.com/webstorm/features/index.html).

My only 'issues'/wishlist items are were:

  1. It seems to be more resource hungry on Mac than Windows It no longer seems an issue in version 6.
  2. It would be nice if it had Snippet support (like those of Sublime Text 2 - i.e. type 'fun' and tap 'tab' to put in a function. See @WickyNilliams comment below - With Live Templates you also have snippet support.

I would use GOOD by Walmart Labs. It will do the job, and it's very flexible:

var hapi = require('hapi');
var good = require('good');
var server = hapi.createServer('localhost', 5000,{});
server.route({SOME ROUTE HERE});
server.start();

var options = {
subscribers: {
    'console':               ['ops', 'request', 'log', 'error'],
    'http://localhost/logs': ['log']
    }
};
server.pack.require('good', options, function (err) {

    if (!err) {
        console.log('Plugin loaded successfully');
    }
});

I wrote a different approach to debug Node.js code which is stable and is extremely simple. It is available at https://github.com/s-a/iron-node.

An opensource cross-platform visual debugger.

Installation:

npm install iron-node -g;

Debug:

iron-node yourscript.js;


If you need a powerful logging library for Node.js, Tracer https://github.com/baryon/tracer is a better choice.

It outputs log messages with a timestamp, file name, method name, line number, path or call stack, support color console, and support database, file, stream transport easily. I am the author.



Start your node process with --inspect flag.

node --inspect index.js

and then Open chrome://inspect in chrome. Click the "Open dedicated DevTools for Node" link or install this chrome extension for easily opening chrome DevTools.

For more info refer to this link




There is built-in command line debugger client within Node.js. Cloud 9 IDE have also pretty nice (visual) debugger.



Using Chrome Version 67.0.3396.62(+)

  1. Run node app

node --inspect-brk=0.0.0.0:9229 server.js(server js filename)

  1. Browse your app in chrome e.g. "localhost:port"
  2. Open DevTools.
  3. Click the the node icon beside the responsive device icon.

There will be another DevTools window that will pop out specifically for debugging node app.





google-chrome-devtools