# Debug

# Chrome Inspector

When working on GraalVM (opens new window) or a JDK with the graalvm (JVMCI) bits, start your application as:

npm start -- -Dinspect=9229

This will start a Chrome inspector debugger agent on port 9229 that you can attach for a remote debug session from your Browser.

Chrome devtools listening at port: 9229
Running: java ...
Debugger listening on port 9229.
To start debugging, open the following URL in Chrome:
Server listening at: http://localhost:8080/


You will be able to set breakpoints, debug etc...

# Debug from VSCode

The usage of Chrome devtools is not a hard requirement. You can also debug the application using Visual Studio Code (opens new window).


Before you can debug from the IDE, you need to install the extension: GraalVM Tools for Java (opens new window) and create a runner configuration.

To create the attach configuration either use the helper command, or use the template bellow:

es4x vscode

This will create a launcher.json similar to this:

  "version" : "0.2.0",
  "configurations" : [ {
    "name" : "Launch empty-project",
    "type" : "graalvm",
    "request" : "attach",
    "port" : 9229
  } ]

And attach your debugger.