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Douglas Crockford's port of QuickCheck to JavaScript

jscheck.js Douglas Crockford 2012-04-24

Public Domain

JSCheck is a testing tool for JavaScript. It was inspired by QuickCheck, a testing tool for Haskell developed by Koen Claessen and John Hughes of Chalmers University of Technology.

JSCheck is a specification-driven testing tool. From a description of the properties of a system, function, or object, it will generate random test cases attempting to prove those properties, and then report its findings. That can be especially effective in managing the evolution of a program because it can show the conformance of new code to old code. It also provides an interesting level of self-documentation, because the executable specifications it relies on can provide a good view of the workings of a program.

All of JSCheck can be loaded from a small file called jscheck.js.

The source is available at The documentation is available at