Pretext

Pretext is a pure JavaScript/TypeScript library that measures and lays out multiline text without triggering expensive DOM operations like getBoundingClientRect or offsetHeight. It implements its own text measurement using the browser's font engine, supporting all languages and Unicode. The library can render to DOM, Canvas, or SVG.

Designed for developers building chat interfaces, editorial layouts, dynamic typography, and other text-heavy UIs, Pretext provides two main APIs: prepare() for one-time text normalization and measurement, and layout() for fast arithmetic-only calculations on resize. The project was developed with AI coding tools, as indicated by its repository configuration.