Aren't things like writing pathfinding algorithms half the fun of making a game?
I released an asynchronous JS pathfinder that handles path priorities and works on much, much larger grid a few years ago: http://lumakey.net/labs/ariane/
Really? Charging $60 for Jump Point Search? I'm almost inclined to copy the API and implement it for free just out of spite.
There was an open source HTML 5 A* with Jump Point Search and others. Forgot the url for now, but I am sure others have seen it.
Though this still looks nice.
Here's a comparable lib that is MIT licensed:
https://github.com/qiao/PathFinding.js
Demo page here: http://qiao.github.io/PathFinding.js/visual/