WebStorm 9: node.js tracing support, superior autocompletion, ES6 tracing support and many other new features.
WebStorm 8: lots of new features and fixed bugs, significant performance and usability improvements.
Ever spent several minutes trying to reproduce some bug and then realised that you didn't set required breakpoint? Tired of stepping into minified jQuery? spy-js allows you to select only scripts and events you're interested in, run your scenario and then inspect collected runtime data like function parameters, return values and exceptions to make your debugging easier.