For library developer

If you haven’t try Closure Tools before, setup can be time consuming and painful. I recommend to read Michael Bolin book’s Closure: The Definitive Guide. A good understanding of closure coding pattern is necessary to understand and follow this library codes.

Apache ant is used to build javascript compiler. ydn-base repo build.xml defines compiler and others tools setting. You must change according to your local machine setting. Specifically check property values of closure-library.dir and closure-compiler.dir, which point to respective directries.

Downloads the following three repos a directory.

svn checkout
git clone
git clone

that should create three directories for closure-library, ydn-base and ydn-db.

Run local apache (recommended) or a static server on that directory.

Go to ydn-db folder and run ant deps and ant ydn-base.deps to generate closure dependency tree.

Use HTML files in the /test folder for getting started. These files are also used for debug development.

Note: we use master track version of closure tools. Compiling with pre-build jar may encounter compile error.

Note: precompile files are built by using custom compiler to strip debug messages. See detail on ydn-base/tools/strip_debug.txt.

Additional features requires the following optional repos.

  1. Full text search
  2. Dependency for ydn-db-fulltext
  3. Dependency for ydn-db-fulltext
  4. Synchronization (private)


You should able to run /ydn-db/test/all-test.html or run individually. Since all test are async, disable run inparallel check box. These test files are for basic testing and debugging.

Coverage test is performed by JsTestDriver test. Notice that ant gen-alltest-js generate jsTestDriver.conf to prepare testing configuration.

java -jar JsTestDriver.jar --tests all

End-to-end testing for disteribution can be found in test/qunit folder as well as online [qunit test kits] (/ydn-db/index/demos.html).


Sending pull request is easiest way. For more, email to one of the authors in the source code.

We follow Google JavaScript Style Guide. All commit on master branch must pass most stringent setting compilation and all unit tests.

Few coding dialect we have as follow:

  • Preferred variable naming is like_this notLikeThis. For function name, useLikeThis as usual.
  • Assume native types (boolean, number, string) are not nullable. If nullable type is used, it is different from undefined. Using undefined for missing value in native type is encourage over null.

Library design

  • Library API should be similar to IndexedDB API and use exact terminology and concept in the IndexedDB specification. So that, people who already familiar with it can pick up immediately as well as go forward with native API.
  • Simple operations should be easy to use as well as optimized for it. Also impose user to use efficient methods while making inefficient ways very difficult or impossible.
  • For complex query, helper utility functions and classes will be provided. Storage class has deep understanding about these helper classes and do optimization behind the sense.
  • Memory efficient and must not use buffer memory. If buffer is used, it must be explicit. Memory leak is unacceptable.
  • Provide extensive error and log message in debug mode, spare no expense since we will strip them in production binary. Error and exception should be thrown as soon as possible, preferable before async callback.
  • Since this API is very simple, fallback to WebSQL and WebStorage should be straight forward. This library design have no consideration for these storage mechanisms.

Bug report

Please file an issue for bug report describing how we could reproduce the problem. Any subtle problem, memory/speed performance issue and missing feature from stand point of IndexedDB API will be considered.

You may also ask question in Stackoverflow #ydn-db with ydb-db hash, or follow on Twitter @yathit.


Licensed under the Apache License, Version 2.0


Kyaw Tun