Node Inspector is a debugger interface for nodeJS using the WebKit Web Inspector.
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- versions: 0.3.0 or later
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A WebKit based browser: Chrome, Safari, etc.
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Optional v8-profiler to use the profiles panel
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With npm
$ npm install -g node-inspector
To use node-inspector, enable debugging on the node you wish to debug. You can either start node with a debug flag like:
$ node --debug your/node/program.js
or, to pause your script on the first line:
$ node --debug-brk your/short/node/script.js
Or you can enable debugging on a node that is already running by sending it a signal:
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Get the PID of the node process using your favorite method.
pgrep
orps -ef
are good$ pgrep -l node 2345 node your/node/server.js
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Send it the USR1 signal
$ kill -s USR1 2345
Great! Now you are ready to attach node-inspector
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start the inspector. I usually put it in the background
$ node-inspector &
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open http://127.0.0.1:8080/debug?port=5858 in your favorite WebKit based browser
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you should now see the javascript source from node. If you don't, click the scripts tab.
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select a script and set some breakpoints (far left line numbers)
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then watch the screencasts
For more information on getting started see the wiki
node-inspector works almost exactly like the web inspector in Safari and Chrome. Here's a good overview of the UI
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I don't see one of my script files in the file list.
try refreshing the browser (F5 or command-r)
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My script runs too fast to attach the debugger.
use
--debug-brk
to pause the script on the first line -
I got the ui in a weird state.
when in doubt, refresh
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Can I debug remotely?
Yes. node-inspector must be running on the same machine, but your browser can be anywhere. Just make sure port 8080 is accessible
--web-port=[port] port to host the inspector (default 8080)
- the WebKit Web Inspector debugger is a great js debugger interface, it works just as well for node
- uses WebSockets, so no polling for breaks
- remote debugging
- javascript top to bottom :)
- edit running code
This is beta quality code, so use at your own risk:
- be careful about viewing the contents of Buffer objects, each byte is displayed as an individual array element, for anything but tiny Buffers this will take too long to render
- while not stopped at a breakpoint the console doesn't always behave as you might expect
VERY EXPERIMENTAL I don't recommend using this yet
To use the profiles panel, install the v8-profiler module:
npm install v8-profiler
To use it do something like:
var profiler = require('v8-profiler');
profiler.startProfiling('startup');
slowStartupFoo();
profiler.stopProfiling('startup');
profiler.takeSnapshot('beforeLeak');
leakyFoo();
profiler.takeSnapshot('afterLeak');
Then view the profiling results with the profiles panel in node-inspector. You can also take heap snapshots on demand from the profiles panel.
This project respectfully uses code from and thanks the authors of: