Node.js debugging

Pittsburghhttp://www.meetup.com/Pittsburgh-Node-js/

Last Wednesday of every month 7-9pmRight here at LeBrew House!

Nicholas McClayDesigner and Developer

@nickmcclay

Debugginggoodbye console.log()

In the beginning there was ‘debugger’

http://nodejs.org/api/debugger.html

To debug in console:

This hook to V8's debugger is what all Node debug tools bind to.

node debug test.jsnote: 'debug' not '--debug', this is a different command we'll see later

Debug command highlights

• Stepping– cont, next, step, out - What you think they do

• Breakpoints– setBreakpoint()/sb() - Set breakpoint on current

line or at statement– clearBreakpoint/clearBreakpoint()/cb(...) - clear

breakpoint (duh)

Debug command highlights

• Info– backtrace/bt - Print backtrace of current execution frame– watch(expr) - Add expression to watch list– unwatch(expr) - Remove expression from watch list– watchers - List all watchers and their values– repl - Open debugger's repl for evaluation in debugging

script's context

• Execution control– run - Run script (automatically runs on debugger's start)– restart - Restart script– kill - Kill script

Can’t we use something a little less…

Arcane? Unusual? Ugly? 1990?

Eclipse IDE

Eclipse Node Debugger Walk Through: https://github.com/joyent/node/wiki/Using-Eclipse-as-Node-Applications-Debugger

Chrome Dev Tools + V8 Debugger:http://code.google.com/p/chromedevtools/

Warning, plug-in compatibility can be a nightmare! Aptana or other highly customized Eclipse based IDE's may not work.

Eclipse advanced debugging

To debug with real source instead of 'VirtualProject' fileshttp://code.google.com/p/chromedevtools/wiki/FeatureDebugOnRealFiles

Screen capture of setuphttp://www.youtube.com/watch?v=GVxFFw7lkYg

Webstorm IDE

Happy Node.js debugging right out of the box!

Coffeescript debugging coming in version 4.0!

Other IDEs

Komodo IDE

node-inspectorWebkit Inspector debugginghttps://github.com/dannycoates/node-inspector

front-end JavaScript debugger reused for back-end JavaScript, what a great idea!

npm install –g node-inspector1.)

node --debug-brk test.js2.)

node-inspector3.)

4.) Open browser to http://localhost:8080/debug?port=5858

Final Thoughts

• --debug vs --debug-brk

• Remote Debugging

• Long stack traceshttp://stackoverflow.com/questions/7697038/more-than-10-lines-in-a-node-js-stack-error

Thanks!

Questions?