Pond.js

Pond.js is a JavaScript and TypeScript library built on `immutable.js`, providing robust, immutable data structures and processing capabilities for time-based data. It unifies the handling of time ranges, events, collections, and time series through specialized types like `TimeRange`, `TimeEvent`, and `TimeSeries`. The library also offers a powerful `Pipeline` API for advanced batch and stream processing, supporting operations such as windowing, grouping, and aggregation. Currently at version 0.9.0, Pond.js is actively developed and ships with comprehensive TypeScript declarations, with the project having been rewritten in TypeScript for its upcoming v1.0 alpha. Its focus on immutability and specialized time-based structures differentiates it for applications requiring consistent and reliable time-series data management.