Tornis is a JavaScript library designed to track various state changes in a user's browser, offering a streamlined alternative to native JavaScript event handlers. Named after Latvia's forest watchtowers, Tornis monitors the viewport state, allowing developers to respond to changes with improved performance and coding experience. By throttling events and capturing only essential updates, Tornis enhances runtime efficiency and simplifies complex event handling. It tracks elements such as mouse position, viewport size, scroll position, and device orientation, enabling developers to create dynamic effects like parallax or mouse velocity-based interactions. The library integrates seamlessly into projects, requiring setup through a package manager and use of modern JavaScript practices like Babel for legacy browser support. A demonstration using Vue.js shows Tornis in action, where a component reacts to mouse velocity changes by altering an emoji's appearance, exemplifying Tornis's capabilities in creating responsive and interactive user experiences.