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Judy Arrays for Node.js

Judy Arrays allow for fast and memory efficient access to in-memory hash tables. This specific Judy implementation is based on work by Karl Malbrain released via the New BSD license. The original work is available Here. Some code cleanup was done to allow for clean compilation with g++.

Instantiation is slow, but continued use shows speed increases over native v8::Array implementation.

For more information, see Faster (sometimes) Associative Arrays with Node.js.

In a nutshell

  • Implements Judy Arrays via C++
  • Adds set/get/delete functionality


node-gyp configure build

Testing and Benchmarking

There are a couple of tests, as well as a couple of benchmarks to compare against native associative arrays.


cd tests
node big.js
node multiple.js


cd benchmark
node native.js
node judy.js

node native.js --count=2000
node judy.js --count=2000



var judy   = require('judy');

var arr = new judy.Judy();
arr.set("some key", "some value");

var value = arr.get("some key");

arr.delete("some key");