This is a drop-in replacement for [LevelDOWN][] that writes to a JSON file on disk.
It also retains the contents of the entire JSON file in memory, so it's only really useful for debugging purposes and/or very small data stores that need just a pinch of persistence.
var levelup = require("levelup");
var db = levelup("./mydata.json", { db: require("jsondown") });
db.put("foo", "bar");