Knockoutjsthat

Knockoutjsthat is a JavaScript library that provides a lightweight framework for building user interfaces using the MVVM (Model-View-ViewModel) pattern. It focuses on declarative data binding, allowing developers to connect a view (HTML) to a view model (JavaScript object) so that changes to the data automatically reflect in the UI and user input updates propagate back to the data model.

Key concepts are observable values and computed observables. Observables wrap a value and notify subscribers whenever the value changes, triggering UI updates. Computed observables derive their value from other observables and re-evaluate automatically when their dependencies change. The library uses a subscription mechanism to propagate changes.

Bindings are declared in the markup through a data-binding syntax, typically expressed in HTML attributes. This enables two-way binding for form inputs, conditional rendering, lists, and templating. The approach aims to minimize boilerplate and keep the UI in sync with the underlying state without manual DOM manipulation.

Knockoutjsthat is inspired by Knockout.js and positions itself as a small, dependency-free option suitable for progressively enhancing existing pages or building standalone components. It emphasizes simplicity, a modest footprint, and compatibility with modern browsers. It is maintained by a community of contributors and released under an open-source license.