ForesightJS is a lightweight, framework-agnostic JavaScript library designed to improve web application performance by predicting user intent and triggering actions before actual interactions occur. It focuses on solving the timing problem in prefetching—determining the optimal moment to load resources so that interfaces feel instant without wasting bandwidth.

Instead of relying on traditional strategies like hover-based or viewport-based prefetching, ForesightJS analyzes user behavior signals such as mouse trajectory, keyboard navigation (tabbing), and scrolling direction. By detecting where a user is likely to interact next, it allows developers to prefetch data, routes, or assets just before the interaction happens, reducing perceived latency.

The library is event-driven and does not rely on polling or heavy computation, making it efficient and suitable for performance-sensitive applications. It supports both desktop and mobile environments, using different prediction strategies depending on input type (mouse, keyboard, or touch).

ForesightJS is implemented through a central manager (ForesightManager) that registers elements and triggers callbacks when intent is detected. Developers define what should happen (e.g., prefetching data), while ForesightJS determines when to trigger it. This separation allows flexible use cases beyond prefetching, such as warming up UI components or starting background tasks.

The library is designed to be small and efficient (~32KB), with optional features and code-splitting to minimize overhead. It integrates with modern frameworks like Next.js and React Router but remains usable in any JavaScript environment.

ForesightJS is positioned as a performance optimization tool for developers who want more precise and efficient prefetching strategies compared to traditional approaches.

Key features include:

• Predicts user intent using mouse movement, keyboard navigation, and scroll behavior
• Triggers callbacks before user interactions occur (pre-hover or pre-click)
• Supports desktop and mobile with adaptive prediction strategies
• Lightweight, event-driven architecture with no polling
• Framework-agnostic with integrations for modern JS frameworks

Common use cases include:

• Prefetching routes or data in web apps
• Improving perceived performance of navigation
• Warming up UI components before interaction
• Optimizing resource loading strategies in frontend applications

ForesightJS is developed as an open-source JavaScript library focused on performance optimization and smarter prefetching for modern web applications.