Viewing and navigation are extremely important to me when I'm reviewing code, whether it's other people's code, my old code, or my questionable new code. WebStorm easily navigates to declarations and symbols, and it finds and highlights usages of symbols, labels, and files.
Configuring Node.js often requires a painful session in the command shell. WebStorm automates Node.js and NPM installation, upgrading, and source code configuration. WebStorm also allows you to debug Node.js applications and autocomplete CommonJS class members.
During debugging, a feature called LiveEdit allows you to change your code and have the changes immediately propagate into the browser where you are running your debug session. This saves time and helps you avoid the common problem of trying to figure out why your change didn't do anything, only to discover that you forgot to refresh your browser.
For unit testing, WebStorm bundles the JsTestDriver plug-in. This was originally a Google project, but JetBrains is now contributing to its development. In addition, WebStorm can integrate with the Karma test runner. For either testing method, WebStorm tracks code coverage.
WebStorm can deploy via FTP, SFTP, FTPS, to local or mounted folders, and in place. WebStorm can download, upload, synchronize, and compare directories and files on demand, and it can automatically upload if you wish.