CountUp.js is a lightweight, dependency-free JavaScript library that animates numerical values by counting toward a target number.
The library solves the problem of displaying animated number transitions in web applications. It works by accepting a target element, an end value, and optional configuration parameters, then smoothly animates the displayed number from its current value to the target. The animation can count upward or downward depending on the start and end values provided. The tool includes smart easing that defers easing effects to make animations visually noticeable, and it can automatically trigger animations when elements become visible on the page.
CountUp.js suits projects that need simple, performant number animations without external dependencies. It works across all browsers and can be integrated into various frameworks including Angular, React, Vue, and Svelte, as well as used directly in vanilla JavaScript, jQuery, WordPress, and custom elements. The library is highly customizable, offering a large range of options including the ability to substitute custom numerals. A plugin system allows for alternate animation styles, such as the Odometer plugin for wheel-style number transitions. The README does not compare it to alternative libraries.
The project maintains active engagement with its codebase through regular updates and refinements to its core animation logic. Development includes ongoing attention to browser compatibility and performance optimization. The tool is documented with clear usage examples and integration guides for multiple frameworks, and it provides interactive demos and sandbox environments for experimentation.
