unpdf

A collection of utilities to work with PDFs. Designed specifically for Deno, workers and other nodeless environments.

unpdf ships with a serverless build/redistribution of Mozilla's PDF.js for serverless environments. Apart from some string replacements and mocks, unenv does the heavy lifting by converting Node.js specific code to be platform-agnostic. See pdfjs.rollup.config.ts for all the details.

This library is also intended as a modern alternative to the unmaintained but still popular pdf-parse.

Features

• 🏗️ Works in Node.js, browser and workers
• 🪭 Includes serverless build of PDF.js (unpdf/pdfjs)
• 💬 Extract text and images from PDFs
• 🧱 Opt-in to legacy PDF.js build
• 💨 Zero dependencies

PDF.js Compatibility

The serverless build of PDF.js provided by unpdf is based on PDF.js v4.6.82. If you need a different version, you can use another PDF.js build.

Installation

Run the following command to add unpdf to your project.

# pnpm
pnpm add unpdf

# npm
npm install unpdf

# yarn
yarn add unpdf

Usage

Extract Text From PDF

import { extractText, getDocumentProxy } from 'unpdf'

// Fetch a PDF file from the web
const buffer = await fetch(
  'https://www.w3.org/WAI/ER/tests/xhtml/testfiles/resources/pdf/dummy.pdf',
).then(res => res.arrayBuffer())

// Or load it from the filesystem
const buffer = await readFile('./dummy.pdf')

// Load PDF from buffer
const pdf = await getDocumentProxy(new Uint8Array(buffer))
// Extract text from PDF
const { totalPages, text } = await extractText(pdf, { mergePages: true })

console.log(`Total pages: ${totalPages}`)
console.log(text)

Access the PDF.js API

This will return the resolved PDF.js module and gives full access to the PDF.js API, like:

• getDocument
• version
• … and all other methods

Especially useful for platforms like 🦕 Deno or if you want to use the PDF.js API directly. If no custom build was defined beforehand, the serverless build bundled with unpdf will be initialized.

import { getResolvedPDFJS } from 'unpdf'

const { getDocument } = await getResolvedPDFJS()
const data = Deno.readFileSync('dummy.pdf')
const doc = await getDocument(data).promise

console.log(await doc.getMetadata())

for (let i = 1; i <= doc.numPages; i++) {
  const page = await doc.getPage(i)
  const textContent = await page.getTextContent()
  const contents = textContent.items.map(item => item.str).join(' ')
  console.log(contents)
}

Use Official or Legacy PDF.js Build

Generally speaking, you don't need to worry about the PDF.js build. unpdf ships with a serverless build of the latest PDF.js version. However, if you want to use the official PDF.js version or the legacy build, you can define a custom PDF.js module.

[!WARNING] The latest PDF.js v4.6.82 uses Promise.withResolvers, which may not be supported in all environments, such as Node < 22. Consider to use the bundled serverless build, which includes a polyfill, or use an older version of PDF.js.

// Before using any other method, define the PDF.js module
// if you need another PDF.js build
import { configureUnPDF } from 'unpdf'

await configureUnPDF({
  // Use the official PDF.js build (make sure to install it first)
  pdfjs: () => import('pdfjs-dist'),
})

// Now, you can use the other methods
// …

Config

interface UnPDFConfiguration {
  /**
   * By default, UnPDF will use the latest version of PDF.js compiled for
   * serverless environments. If you want to use a different version, you can
   * provide a custom resolver function.
   *
   * @example
   * // Use the official PDF.js build (make sure to install it first)
   * () => import('pdfjs-dist')
   */
  pdfjs?: () => Promise<PDFJS>
}

Methods

configureUnPDF

Define a custom PDF.js module, like the legacy build. Make sure to call this method before using any other methods.

function configureUnPDF(config: UnPDFConfiguration): Promise<void>

getResolvedPDFJS

Returns the resolved PDF.js module. If no build is defined, the latest version will be initialized.

function getResolvedPDFJS(): Promise<PDFJS>

getMeta

function getMeta(
  data: DocumentInitParameters['data'] | PDFDocumentProxy,
): Promise<{
  info: Record<string, any>
  metadata: Record<string, any>
}>

extractText

Extracts all text from a PDF. If mergePages is set to true, the text of all pages will be merged into a single string. Otherwise, an array of strings for each page will be returned.

function extractText(
  data: DocumentInitParameters['data'] | PDFDocumentProxy,
  { mergePages }?: { mergePages?: boolean },
): Promise<{
  totalPages: number
  text: string | string[]
}>

renderPageAsImage

[!NOTE] This method will only work in Node.js and browser environments.

To render a PDF page as an image, you can use the renderPageAsImage method. This method will return an ArrayBuffer of the rendered image.

In order to use this method, you have to meet the following requirements:

• Use the official PDF.js build
• Install the canvas package in Node.js environments

Example

import { configureUnPDF, renderPageAsImage } from 'unpdf'

await configureUnPDF({
  // Use the official PDF.js build
  pdfjs: () => import('pdfjs-dist'),
})

const pdf = await readFile('./dummy.pdf')
const buffer = new Uint8Array(pdf)
const pageNumber = 1

const result = await renderPageAsImage(buffer, pageNumber, {
  canvas: () => import('canvas'),
})
await writeFile('dummy-page-1.png', result)

Type Declaration

declare function renderPageAsImage(
  data: DocumentInitParameters['data'],
  pageNumber: number,
  options?: {
    canvas?: () => Promise<typeof import('canvas')>
    /** @default 1 */
    scale?: number
    width?: number
    height?: number
  },
): Promise<ArrayBuffer>

FAQ

Why Is canvas An Optional Dependency?

The official PDF.js library depends on the canvas module for Node.js environments, which doesn't work inside worker threads. That's why unpdf ships with a serverless build of PDF.js that mocks the canvas module.

However, to render PDF pages as images in Node.js environments, you need to install the canvas module. That's why it is a peer dependency.

License

MIT License © 2023-PRESENT Johann Schopplich