Debugging the Main Process in node-inspector

Debugging the Main Process in node-inspector

node-inspector provides a familiar DevTools GUI that can be used in Chrome to debug Electron’s main process, however, because node-inspector relies on some native Node modules they must be rebuilt to target the version of Electron you wish to debug. You can either rebuild the node-inspector dependencies yourself, or let electron-inspector do it for you, both approaches are covered in this document.

Note: At the time of writing the latest release of node-inspector (0.12.8) can’t be rebuilt to target Electron 1.3.0 or later without patching one of its dependencies. If you use electron-inspector it will take care of this for you.

Use electron-inspector for Debugging

1. Install the node-gyp required tools

2. Install electron-rebuild, if you haven’t done so already.

npm install electron-rebuild --save-dev

3. Install electron-inspector

npm install electron-inspector --save-dev

4. Start Electron

Launch Electron with the --debug switch:

electron --debug=5858 your/app

or, to pause execution on the first line of JavaScript:

electron --debug-brk=5858 your/app

5. Start electron-inspector

On macOS / Linux:

node_modules/.bin/electron-inspector

On Windows:

node_modules\\.bin\\electron-inspector

electron-inspector will need to rebuild node-inspector dependencies on the first run, and any time you change your Electron version. The rebuild process may require an internet connection to download Node headers and libs, and may take a few minutes.

6. Load the debugger UI

Open http://127.0.0.1:8080/debug?ws=127.0.0.1:8080&port=5858 in the Chrome browser. You may have to click pause if starting with --debug-brk to force the UI to update.

Use node-inspector for Debugging

1. Install the node-gyp required tools

2. Install node-inspector

$ npm install node-inspector

3. Install node-pre-gyp

$ npm install node-pre-gyp

4. Recompile the node-inspector v8 modules for Electron

Note: Update the target argument to be your Electron version number

$ node_modules/.bin/node-pre-gyp --target=1.2.5 --runtime=electron --fallback-to-build --directory node_modules/v8-debug/ --dist-url=https://atom.io/download/atom-shell reinstall
$ node_modules/.bin/node-pre-gyp --target=1.2.5 --runtime=electron --fallback-to-build --directory node_modules/v8-profiler/ --dist-url=https://atom.io/download/atom-shell reinstall

See also How to install native modules.

5. Enable debug mode for Electron

You can either start Electron with a debug flag like:

$ electron --debug=5858 your/app

or, to pause your script on the first line:

$ electron --debug-brk=5858 your/app

6. Start the node-inspector server using Electron

$ ELECTRON_RUN_AS_NODE=true path/to/electron.exe node_modules/node-inspector/bin/inspector.js

7. Load the debugger UI

Open http://127.0.0.1:8080/debug?ws=127.0.0.1:8080&port=5858 in the Chrome browser. You may have to click pause if starting with --debug-brk to see the entry line.