AlaSQL
JavaScript SQL database for browser and Node.js for relational tables
...Real-world solutions demand flexibility regarding where data comes from and where it is to be stored. We focus on flexibility by making sure you can import/export and query directly on data stored in Excel (both .xls and .xlsx), CSV, JSON, TAB, IndexedDB, LocalStorage, and SQLite files. The library adds the comfort of a full database engine to your JavaScript app. No, really - it's working towards a full database engine complying with most of the SQL-99 language, spiced up with additional syntax for NoSQL (schema-less) data and graph networks.