Make sure you have Node.js on your computer. This enables Spy-js to intercept and modify script requests and scripts, whereupon the tracing procedure runs as when tracing a website script. Therefore to trace a Node.js application, spy-js launches the Node.js server and the application itself. In case of a Node.js application, Spy-js cannot get between the Node.js server and the scripts if the application is already running. When you open a traced website in your browser, Spy-js receives the script request, requests the script from your website, receives the script, makes the required modifications, and sends it back to your browser where the script executes, and sends the runtime information to the Spy-js UI. To modify website scripts, Spy-js has to act as a proxy server that 'sits' between your browser and the website you are tracing. Spy-js uses different mechanisms for tracing Web applications and Node.js applications.

To trace a script, Spy-js modifies it on the fly by inserting instrumentation instructions that report back to Spy-js UI about what functions have been invoked when the script executes. With WebStorm, you can trace your applications during a SpyJS-specific debugging session and explore the results in the dedicated UI. See Debugging CoffeeScript and File Watchers for details. Spy-js recognizes source maps so you can trace applications with CoffeeScript and TypeScript code. Spy-js is a tool for debugging, tracing, and profiling JavaScript running on different platforms/browsers/devices as well as server-side Node.js applications.

Jetbrains javascript