Pretext

Pretext is an open-source TypeScript library designed to revolutionize web text layout. It allows for multiline text measurement and layout entirely in 'userland,' bypassing the browser's Document Object Model (DOM) and its associated performance bottlenecks. This enables dynamic, interactive, and responsive text elements that can adapt and move smoothly around other objects on a webpage, even under complex conditions like user interaction or window resizing. Pretext achieves this by using the browser's Canvas font metrics engine as a ground truth and combining it with pure arithmetic, predicting text geometry without touching DOM nodes. It offers a significant performance increase (300-600x) compared to traditional DOM reads, transforming layout from a heavy chore into a fast, predictable primitive.