Building a native module (node-gyp) with debug symbols

cd node_modules/module
node-gyp rebuild --debug

(You might have to adjust require paths from Release to Debug.)

Building node with debug symbols

Download sources and run:

./configure --debug

Then run using the node_g binary (a symlink to out/Debug/node).

Note that you might think that this would work:

nvm install -s <version> --debug

But nope, that actually still installs the release build of node.