As a keyboard shortcut addict, I like when I’m able to go quickly through blog posts of a website using the left and right arrows keys. I find that keyboard navigation is particularly useful on photo blogs for instance.
Below is the PHP code to enable keyboard navigation for single posts in WordPress.
Below is the JS code to enable keyboard navigation for single posts in WordPress.
Alternatively, you can download and install WP Keyboard Navigation from the WordPress Plugin Repository. Also, if you are interested in further control of the previous/next links displayed on single posts, you might want to have a look at the WordPress Codex here and there.