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Node.js debugger into VS Code

node --inspect

To enable Node's debug mode, we should execute node with the --inspect flag.

Let's add that flag to our npm run dev script into package.json file, generated by irongenerate:

    "dev": "DEBUG=starter-code:* nodemon --inspect ./bin/www"

Without having to modify that line, we can also pass the flag by executing the command npm run dev -- --inspect but it's longer and we have to remember it every time (see the npm-run-script doc about.)

Auto Attach

In VS Code's preferences, we set the Node: Auto Attach setting to on:

Debug now🐛

From a VS Code terminal, we now launch the command npm run dev:

The command outputs: Debugger listening on port 9229.

We can now set some breakpoints, by clicking on the line we want to debug:

🔴 The red point to the left of the line 71 indicates that a breakpoint is now set to.

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When a request will call that line of code, the debugger will pause the program and will allow us to inspect our variables values, do some step-by-step… etc:

devTools alternative

If we don't want to use VS Code to debug, Chrome devTools is also possible:

• Go to URL: chrome://inspect
  
• then click on the inspect link on the corresponding remote target :