flyd

Flyd is a lightweight JavaScript library designed to support functional reactive programming by providing simple, composable streams. It aims for a small API surface and a straightforward model for reactive data flows, making it suitable for small to medium web projects and for experimentation with FRP concepts.

In flyd, a stream represents a value that can be observed and updated. A stream is typically implemented as a function: calling the stream with a value pushes that value into the stream, while calling it without arguments reads the most recent value. Streams can be connected to one another to form dependency graphs, enabling automatic propagation of changes through the system.

The library provides mechanisms to create streams, transform them with functions to produce derived streams, and combine multiple streams into new ones. Subscribing to streams allows code to react to new values as they arrive. This makes flyd well-suited for building reactive user interfaces where data changes should trigger updates without requiring a large framework.

Flyd emphasizes minimalism and clarity, prioritizing a direct approach to composing reactive data flows. It is designed to be used alongside existing JavaScript code and libraries, serving as a compact reactive core rather than a full-stack framework.

See also: Functional reactive programming; Reactive programming; Streams in computing.