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Install the package

The npm package name is @chenglou/pretext. 
npm install @chenglou/pretext

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Import the named exports

import { prepare, layout, prepareWithSegments, layoutWithLines, layoutNextLine, walkLineRanges, clearCache, setLocale } from '@chenglou/pretext'
You only need to import the functions relevant to your use case. For height prediction, prepare and layout are sufficient. For manual rendering, also import prepareWithSegments and one of the line layout functions.

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TypeScript support

Pretext ships declaration files automatically as of version 0.0.3. No @types/ package or additional configuration is required — TypeScript consumers pick up the types directly from the published package.

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ESM-only package

Pretext is an ESM-only package ("type": "module" in package.json). It is distributed as built JavaScript from dist/layout.js with matching declaration files. CommonJS require() is not supported.
If your bundler or runtime requires CJS interop, use a dynamic import() or configure your build tool to handle ESM dependencies.

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Browser environment requirement

Pretext requires a browser environment. It uses two browser-only APIs that are not available in Node.js without polyfills:
  • canvas.measureText — used by prepare() and prepareWithSegments() to measure segment widths against the real font engine.
  • Intl.Segmenter — used to segment text into words and graphemes for CJK, Thai, Arabic, and other scripts.
Server-side rendering support is planned for a future release. For now, call prepare() in the browser, after fonts have loaded.

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