# 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:
    chrome-devtools://devtools/bundled/js_app.html?ws=127.0.0.1:9229/436e852b-329b5c44c3e
Server listening at: http://localhost:8080/

chrome-inspector

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).

WARNING

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.

vscode-chrome-inspector

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