AlaSQL
JavaScript SQL database for browser and Node.js for relational tables
... 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.