In the recently released "Field Guide to Web Applications" (from the Google Chrome team), the authors mention the "emergent convention of the J and K keys to move forward and backward" in a web app. This is new to me. I tested it on the Field Guide web app itself, and was surprised to find that (contrary to my intuition) the J-key is forward and the K-key is back. I suppose this comes from "K" being associated with the word BACK_ and "J" resembling the return arrow on the enter key (or a page turn indicator). But given their respective location on the keyboard, this navigational association seems backwards to me. Is this, as Google contends, an emerging trend? Have you seen other web-pages or web-apps that support this? Would you recommend it?
It is a convention which was popularised by the text editor vi, precursor to Vim.
To quote Stack Overflow user martin clayton from this highly related (but not exact duplicate) question
Bill joy, who wrote the visual mode of ex - which ended up being vim precursor vi - used a Lear Siegler ADM3A terminal on which the H, J, K, L keys mapped to left, down, up, right - and its been that way ever since.
Some examples of awesome sites which use this convention:
You can use any key on the keyboard as a shortcut key in a web application it's up to you to decide what letters do what. A popular script is jQuery hot keys https://github.com/jeresig/jquery.hotkeys