sql-js/sql.js: A javascript library to run SQLite on the web. @GitHub
sql.js is a javascript SQL database. It allows you to create a relational database and query it entirely in the browser. You can try it in this online demo. It uses a virtual database file stored in memory, and thus doesn't persist the changes made to the database. However, it allows you to import any existing sqlite file, and to export the created database as a JavaScript typed array.
sql.js uses emscripten to compile SQLite to webassembly (or to javascript code for compatibility with older browsers). It includes contributed math and string extension functions.