One way to debug a Node js Application (e.g., Sail.js) is using the debug capabilities of Node.js (version 6.3.0+) and the integration with Chrome DevTools (as they both share the same V8 Javascript Engine). Thus, you can debug your application running alongside with other development tools like webpack-dev-server, angular-cli server, loggers, and others.

You can take a look at the complete configuration of the Angular + Sails starter, for debugging a Sails app.

The following steps describe how to set up the package.json scripts to start debugging with a single command from the console,

  1. Open a terminal and go to sails directory.
  2. First, we need to run node with "--inspect" flag to inspect the code inside chrome's DevTools. So we need to run,

node --inspect app.js

To get sails up and running.
However, we might be missing webpack dev-server or any other middleware process.

  1. Modify package.json's scripts adding the following lines,
"start:debug" : "npm-run-all --parallel open:client debug",
...
"debug": "node --inspect app.js"

The complete scripts sections looks like this,

"start": "npm-run-all --parallel open:client dev",
    "start:debug" : "npm-run-all --parallel open:client debug",
    "open:client" : "ng serve --open",
    "build": "npm run build:prod",
    "build:dev": "ng build --deploy-url=dist",
    "build:prod": "ng build --prod --deploy-url=dist",
    "build:aot": "ng build --aot --deploy-url=dist",
    "clean": "rimraf assets/dist",
    "prod": "sails lift --prod",
    "dev": "sails lift --dev",
    "debug": "node --inspect app.js"

This way, we can just run "npm run start:debug" and run Sails normally as we usually do but featuring debugging.
You should see something like the following,

debug-sails

It prompts you to open the long URL chrome-devtools://... in the browser but doesn't. Instead open "about:inspect" in Chrome

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Click on Open dedicated DevTools for Node to open a new DevTools window,

debug-sails2--1-

Here you can access all the code from the project and set breakpoints, step-in, step-out, inspect variables, javascript profiler, heap allocation timeline and all you can do when debugging Javascript client code in chrome.

That's it!. Now you can debug Sails.js in Devtools!.