You might want to check out Zeal. I just started implementing it this weekend. It's intended to be a documentation browser like Dash, working on Linux.
Here is a screenshot:
devhelp may help you
Devhelp is an API documentation browser for GTK+ and GNOME. It works natively with gtk-doc (the API reference framework developed for GTK+ and used throughout GNOME for API documentation). If you use gtk-doc with your project, you can use Devhelp to browse the documentation.
For JQuery there is JQAPI. You can even install it as package!
$ sudo apt-get install jquery-alternative-doc
Then browse to this file in your browser.
If you use emacs then give helm-dash a try.