如何修改Node.js默认调试器端口？解决9229端口占用报错

Hey there! Let's break down how to change Node.js's default debugger port and fix that "address already in use" error you're seeing.

There are a few straightforward ways to override the default 9229 port for the Node.js inspector:

• Command line direct specification: When starting your app, append the --inspect flag with your desired port. For example:

  node --inspect=9230 app.js
  

  If you need to allow connections from external devices (not just localhost), you can bind to all addresses like this:

  node --inspect=0.0.0.0:9230 app.js
  

  Note: For older Node.js versions (pre-v7), use --debug=9230 instead, though the inspect API is now the standard.

• Package.json script configuration: If you use npm scripts to start your app, update the script to include the port flag. For example:

  {
    "scripts": {
      "start": "node --inspect=9230 app.js"
    }
  }
  

  Now running npm start will automatically use your custom port.

• Environment variable: Set the NODE_INSPECT_PORT environment variable before launching Node.js:

  • On Linux/macOS (bash/zsh):

    export NODE_INSPECT_PORT=9230
    node app.js
    

  • On Windows (Command Prompt):

    set NODE_INSPECT_PORT=9230
    node app.js
    

  • On Windows (PowerShell):

    $env:NODE_INSPECT_PORT=9230
    node app.js
    

This error means another process is already using port 9229. Here's how to fix it:

Option 1: Kill the process using port 9229 #

First, find out which process is hogging the port:

• Linux/macOS:
  Use lsof to list processes using the port:

  lsof -i :9229
  

  Look for the PID column, then kill the process with:

  kill -9 <PID>
  

  If you get a permission error, add sudo before the commands.

  Alternatively, use netstat:

  netstat -tulpn | grep 9229
  

• Windows:
  In Command Prompt, run:

  netstat -ano | findstr :9229
  

  The last number in the output is the PID. Kill the process with:

  taskkill /F /PID <PID>
  

  Or open Task Manager, go to the "Details" tab, find the process with that PID, and end it.

Option 2: Use a different port instead #

If you don't want to kill the existing process, just start your Node app with a custom port as we covered earlier. For example:

node --inspect=9230 app.js

Pro tip: Sometimes the stuck process is a leftover Node.js instance that didn't exit properly. Killing it should resolve the issue for future launches on the default port.

内容的提问来源于stack exchange，提问作者Sasi Rekha