BrowserCouch is an attempt at an in-browser MapReduce implementation. It's written entirely in JavaScript and intended to work on all browsers, gracefully upgrading when support for better efficiency or feature set is detected.

Not coincidentally, this library is intended to mimic the functionality of CouchDB on the client-side, and may even support integration with CouchDB in the future.

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To learn how to use BrowserCouch, check out the work-in-progress tutorial.