JSCS
Required plugins:
Javascript and TypeScript - The plugin is bundled with RubyMine and enabled by default.
JSCS - Install the plugin on the Settings/Preferences | Plugins page, tab Marketplace.
warning
Since RubyMine 2020.2, JSCS support in the IDE has been deprecated, see the JSCS official website for details.
However, JSCS support is still available through the JSCS plugin, which can be installed on the Settings/Preferences | Plugins page as described in Installing plugins from JetBrains repository.