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The Absolute Easiest Way to Debug Node.js – With VS Code

97 points by yannikyeo 8y ago

Waterluvian 8y ago
ROS distributes robot concerns across dozens of nodes on a robot, possibly thousands of nodes in a fleet. Many of these are Python. It's been a joy using vscode to connect to a live running robot and the master server and remote debug a bunch of nodes at the same time.
devnill 8y ago
While VS Code is a great IDE, a lot of this article is simply untrue. Node has had an interactive debugger (and corresponding API) for years. Prior to --inspect, --debugger gave developers the abilities to step through code and to jump into a REPL to examine and manipulate the application state. Beyond this, there were tools like node inspector(https://github.com/node-inspector/node-inspector https://github.com/node-inspector/node-inspector) which provided a chrome inspector-like tool. On top of that, these tools adhere to the chrome debugger API (https://chromedevtools.github.io/devtools-protocol/ https://chromedevtools.github.io/devtools-protocol/) which provides the ability to dump comprehensive data like the memory graph for those wishing to make profiling tools.
brian_herman 8y ago
https://nodejs.org/api/debugger.html https://nodejs.org/api/debugger.html
chrisparton1991 8y ago
> Unlike JavaScript in the browser, or Java with a powerful IDE like IntelliJ, you can’t just set breakpoints everywhere I'm using IntelliJ to set breakpoints everywhere in a Node application at this very moment. It's super easy to set up, you just create a Node.js run configuration and hit the debug button.
- orf 8y ago
  Same here, but with Python. The IntelliJ debugger is one of the absolute best features and I haven't found anything comparable yet.
- np_tedious 8y ago
  How does this work with transpilation? Say I have typescript or a just different js than the end build, how does the debugger know which line to put the breakpoint on? Does the run config need to be something more structured than "run this gulp command"?
  - mikewhy 8y ago
    Pretty sure all you need is source maps.
    - chrisparton1991 8y ago
      Yep, source maps do the trick.
      - np_tedious 8y ago
        late response, but i just got stop debugging for a typescript/node app set up in webstorm. far easier than i (and this article) had built it up to be. the sourcemap stuff was actually already taken care of, it was the addition of `$NODE_DEBUG_OPTION` to the `ts-node-dev` command that did the trick
- snackman7 8y ago
  You can do this in VS Code as well. You create a launch.json file, and you can debug. A basic launch.json file is like 3 lines long, and VS Code makes it for you. There's no need for an extension. Maybe the author wasn't aware of that.
paulirish 8y ago
The author linked to a post of mine for debugging Node with Chrome DevTools I agree that it's a little frustrating. But a few months ago, the `ndb` project launched with a phenomenally better user experience for this: https://github.com/GoogleChromeLabs/ndb https://github.com/GoogleChromeLabs/ndb It has child processes support, easy Ctrl-R hotkey to restart your node, breakpoints can be placed anywhere, and nice default blackboxing of node internals. Worth a spin.
- newsbinator 8y ago
  'ndb' is so, so much better. You've just put something amazing in front of me. Thank you!!
- emilsedgh 8y ago
  Read the article and came back to mention `ndb`. Cannot emphasis how easy it is to debug with it. If you're using node, do yourself a favor and `npx ndb` next time you wanna debug something.
mlevental 8y ago
is there a way to debug promises in any of these debuggers? i.e. get a promise to resolve when stopped at a breakpoint?
- giobox 8y ago
  The “Smart Step” feature they added to the debugger a while back might be what you are looking for. > https://code.visualstudio.com/updates/vApril#_smart-code-stepping https://code.visualstudio.com/updates/vApril#_smart-code-ste...
  - mlevental 8y ago
    no this isn't it. i'm saying i want to be able to "run" a promise while stopped at breakpoint
- EGreg 8y ago
  How do I make my code not trigger the debugger breakpoint whenever a promise fails? I get that the fail isn’t being handled but isn’t there to make a default handler in that case?
tluyben2 8y ago
Honest question: is there anyone here who uses Node that didn't figure this out themselves with VS Code or other editors in a few minutes? And then a lot of the info is (as already mentioned here as well) not true; this is nothing new nor special.
keyle 8y ago
This is just highly biased. It's just as easy with IntelliJ and doesn't require any more fiddling around than this.

97 points by yannikyeo 8y ago

ROS distributes robot concerns across dozens of nodes on a robot, possibly thousands of nodes in a fleet. Many of these are Python. It's been a joy using vscode to connect to a live running robot and the master server and remote debug a bunch of nodes at the same time.

devnill 8y ago

While VS Code is a great IDE, a lot of this article is simply untrue. Node has had an interactive debugger (and corresponding API) for years. Prior to --inspect, --debugger gave developers the abilities to step through code and to jump into a REPL to examine and manipulate the application state. Beyond this, there were tools like node inspector(https://github.com/node-inspector/node-inspector https://github.com/node-inspector/node-inspector) which provided a chrome inspector-like tool. On top of that, these tools adhere to the chrome debugger API (https://chromedevtools.github.io/devtools-protocol/ https://chromedevtools.github.io/devtools-protocol/) which provides the ability to dump comprehensive data like the memory graph for those wishing to make profiling tools.

brian_herman 8y ago

https://nodejs.org/api/debugger.html https://nodejs.org/api/debugger.html

chrisparton1991 8y ago

> Unlike JavaScript in the browser, or Java with a powerful IDE like IntelliJ, you can’t just set breakpoints everywhere I'm using IntelliJ to set breakpoints everywhere in a Node application at this very moment. It's super easy to set up, you just create a Node.js run configuration and hit the debug button.

orf 8y ago
Same here, but with Python. The IntelliJ debugger is one of the absolute best features and I haven't found anything comparable yet.
np_tedious 8y ago
How does this work with transpilation? Say I have typescript or a just different js than the end build, how does the debugger know which line to put the breakpoint on? Does the run config need to be something more structured than "run this gulp command"?
- mikewhy 8y ago
  Pretty sure all you need is source maps.
  - chrisparton1991 8y ago
    Yep, source maps do the trick.
    - np_tedious 8y ago
      late response, but i just got stop debugging for a typescript/node app set up in webstorm. far easier than i (and this article) had built it up to be. the sourcemap stuff was actually already taken care of, it was the addition of `$NODE_DEBUG_OPTION` to the `ts-node-dev` command that did the trick
snackman7 8y ago
You can do this in VS Code as well. You create a launch.json file, and you can debug. A basic launch.json file is like 3 lines long, and VS Code makes it for you. There's no need for an extension. Maybe the author wasn't aware of that.

paulirish 8y ago

The author linked to a post of mine for debugging Node with Chrome DevTools I agree that it's a little frustrating. But a few months ago, the `ndb` project launched with a phenomenally better user experience for this: https://github.com/GoogleChromeLabs/ndb https://github.com/GoogleChromeLabs/ndb It has child processes support, easy Ctrl-R hotkey to restart your node, breakpoints can be placed anywhere, and nice default blackboxing of node internals. Worth a spin.

newsbinator 8y ago
'ndb' is so, so much better. You've just put something amazing in front of me. Thank you!!
emilsedgh 8y ago
Read the article and came back to mention `ndb`. Cannot emphasis how easy it is to debug with it. If you're using node, do yourself a favor and `npx ndb` next time you wanna debug something.

mlevental 8y ago

is there a way to debug promises in any of these debuggers? i.e. get a promise to resolve when stopped at a breakpoint?

giobox 8y ago
The “Smart Step” feature they added to the debugger a while back might be what you are looking for. > https://code.visualstudio.com/updates/vApril#_smart-code-stepping https://code.visualstudio.com/updates/vApril#_smart-code-ste...
- mlevental 8y ago
  no this isn't it. i'm saying i want to be able to "run" a promise while stopped at breakpoint
EGreg 8y ago
How do I make my code not trigger the debugger breakpoint whenever a promise fails? I get that the fail isn’t being handled but isn’t there to make a default handler in that case?

tluyben2 8y ago

Honest question: is there anyone here who uses Node that didn't figure this out themselves with VS Code or other editors in a few minutes? And then a lot of the info is (as already mentioned here as well) not true; this is nothing new nor special.

keyle 8y ago

This is just highly biased. It's just as easy with IntelliJ and doesn't require any more fiddling around than this.