bugger

Warning: Experimental

bugger provides Chrome Devtools bindings for node. It integrates tightly with Chrome which means two things:

• It attempts to fully support the usual Devtools experience, including workspaces and profiling tools.
• It may break at any moment because Chrome moves fast.

Installation

npm install -g bugger

Usage

Start the script process

Start example/alive.js in debug mode:

bugger example/alive.js

Pass parameters to the script:

# This will be interpreted as a port paramter for alive.js
bugger example/alive.js --port=3000
# This will be interpreted as a port paramter for bugger itself
bugger --port=3000 example/alive.js

Pass V8 options (or advanced node options):

node --trace_gc $(which bugger) example/alive.js

Open the devtools

The correct URL will be written to the output. It should look similar to this:

chrome-devtools://devtools/bundled/devtools.html?ws=127.0.0.1:8058/websocket

You can also open chrome://inspect if you started Chrome with --remote-debugging-targets=localhost:8058. The process should pop up on that page almost immediately.

Options:

• -v, --version: Print version information
• -h, --help: Show usage help
• -p, --port: The devtools protocol port to use, default: 8058
• -b, --brk: Pause on the first line of the script

Features

Console Tab

• Basic support for console API
• Evalute expressions in the console
• Fully featured repl when not paused (including require)
• Parts of the Command Line API supported

Sources Tab

• Step-by-step debugging
• Variable introspection
• Live edit the running JavaScript code and persist it using workspaces (really just a Devtools feature)
• Break on [uncaught] exception
• Uses existing source maps (e.g. created via babel --source-maps or coffee --map)
• Forked modules show up as worker threads. This includes modules forked via cluster.

Known Issues

• For babel-core/register and coffee-script/register, editing the files doesn't work #48

Network Tab

• Monitor outgoing http(s) requests your script does
• Timing of requests, including connect times etc.

Timeline Tab

• GC events
• Basic heap usage graphs

Known Issues

• The timeline tab doesn't do anything useful right now. In future it should show (#47):
  • console.{time, timeEnd, timeStamp}
  • Network request
  • Heap usage over time
  • Profiling data

Profiles Tab

• Heap snapshots
• CPU profiles
• Track heap allocations
• Inspect heap objects in the console via $0..$4

Kudos to...

...the original projects

bugger was heavily inspired by node-inspector and nodebug.

Reference links

• https://chromium.googlesource.com/chromium/blink.git
• http://chromedevtools.github.io/debugger-protocol-viewer/Debugger/
• https://github.com/nodejs/node