ndp

Overview ¶

Ndp debugs Node.js processes and Chrome browsers over the inspector protocol.

Node and Chrome speak the same wire protocol, so ndp drives both: attach to a running Node process or a browser tab, set watches, evaluate expressions, profile, and inspect the V8 runtime. Use it for server-side JavaScript, where cmd/cdp and cmd/chdb are aimed at pages.

Usage:

ndp <command> [flags] [arguments]

Every command has its own flags and help text:

ndp help
ndp help <command>
ndp <command> --help

Node.js ¶

node start <script.js>       Start a script with debugging enabled
node attach [port]           Attach to a running process
node list                    List active Node.js debug sessions
node watch <port> <expr>     Add a watch expression
node sessions                List active debug sessions

Chrome ¶

chrome attach [port]         Attach to a browser
chrome list                  List tabs and targets
chrome navigate <url>        Navigate to a URL
chrome console <js>          Evaluate JavaScript in the console

Targets and sessions ¶

targets                      List all debug targets
session list                 List attach session files
repl                         Start an interactive REPL
tui                          Start the terminal UI
search                       Search loaded scripts

The V8 runtime ¶

v8 [command]                         V8 Inspector debugging,
                                     compatible with Chrome DevTools
runtime evaluate <expr>              Evaluate an expression
runtime compile <port> <expr>        Compile a script and print its ID
runtime run <port> <script-id>       Run a compiled script
runtime call <port> <object-id> <fn> Call a function on a remote object
runtime release-object <port> <id>   Release a remote object
runtime release-group <port> <group> Release a remote object group
runtime disable <port>               Disable the runtime domain

Profiling and raw access ¶

profile cpu [duration]       Profile the CPU for a duration (default 10s)
                             and write the profile to -o
                             (default cpu-profile.json)
profile heap                 Take a heap snapshot and write it to -o
                             (default heap-snapshot.json)
call <method> [json]         Execute a raw CDP method, for anything the
                             commands above do not cover
proxy                        Start a WebSocket proxy between a CDP client
                             and the target, to inspect the DevTools
                             traffic itself