ResizeListener is a JavaScript library that provides an efficient way to instantly react to changes in element size. It uses hidden elements that exploit scrollbar behavior which allows for a completely event-driven way of detecting size changes. View the GitHub page for information and API documentation.

Event-Based Does not constantly poll the DOM for changes Universal Detects all changes in size regardless of what caused them Cross-Browser Tested in IE5+, Chrome, FireFox, Safari, and Opera Light Weight Only 1.13KB (gzipped)