WebStorm is a popular IDE by JetBrains (http://www.jetbrains.com/webstorm/), and will run on Windows, macOS, and Linux. Prices range from $59 per year for a single developer to $129 per year for a commercial license. JetBrains also offers a 30-day trial version.

WebStorm has a couple of great features, including live edit, code refactoring suggestions, and Intellisense. Live edit, in particular, allows you to keep a browser open that will automatically update based on changes to CSS, HTML, and JavaScript as you type it. Code suggestions, which are also available with another popular JetBrains product, ReSharper, will highlight code that you have written and suggest better ways of implementing it. WebStorm also has a large number of project templates, which are seamlessly integrated into the IDE, automatically downloading and including the relevant JavaScript or CSS files in your project.

On Windows systems, setting up WebStorm is as simple as downloading the package from the website, and running the installer. On Linux systems, Webstorm is provided as a tar ball. Once unpacked, install WebStorm by running the webstorm.sh script in the bin directory. Note that on Linux systems, a running version of Java must be installed before setup will continue.