https://github.com/johannschopplich/pdfjs-serverless
🪠Serverless build of PDF.js for Deno, workers, and other nodeless environments
https://github.com/johannschopplich/pdfjs-serverless
Last synced: 6 months ago
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🪠Serverless build of PDF.js for Deno, workers, and other nodeless environments
- Host: GitHub
- URL: https://github.com/johannschopplich/pdfjs-serverless
- Owner: johannschopplich
- License: mit
- Created: 2023-08-26T18:46:54.000Z (about 2 years ago)
- Default Branch: main
- Last Pushed: 2025-03-02T19:29:06.000Z (7 months ago)
- Last Synced: 2025-03-29T07:02:13.820Z (6 months ago)
- Language: TypeScript
- Homepage:
- Size: 357 KB
- Stars: 75
- Watchers: 1
- Forks: 4
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# pdfjs-serverless
A redistribution of Mozilla's [PDF.js](https://github.com/mozilla/pdf.js) for serverless environments, like Deno Deploy and Cloudflare Workers with zero dependencies. The whole export is about 1.4 MB (minified).
## PDF.js Compatibility
> [!NOTE]
> This package is currently using PDF.js v4.10.38.
## Installation
Run the following command to add `pdfjs-serverless` to your project.
```bash
# pnpm
pnpm add pdfjs-serverless
# npm
npm install pdfjs-serverless
# yarn
yarn add pdfjs-serverless
```
## Usage
Since PDF.js v4, the library migrated to ESM. Which is great. However, it also uses a top-level await, which is not supported by Cloudflare workers yet. Therefore, we have to wrap all named exports in a function that resolves the PDF.js library:
```ts
declare function resolvePDFJS(): Promise
```
So, instead of importing the named exports directly:
```ts
// This will NOT work at the moment
import { getDocument } from 'pdfjs-serverless'
```
We have to use the `resolvePDFJS` function to get the named exports:
```ts
import { resolvePDFJS } from 'pdfjs-serverless'
const { getDocument } = await resolvePDFJS()
```
> [!NOTE]
> Once Cloudflare workers support top-level await, we can remove this wrapper and re-export all PDF.js named exports directly again.
### 🦕 Deno
```ts
import { resolvePDFJS } from 'https://esm.sh/pdfjs-serverless'
// Initialize PDF.js
const { getDocument } = await resolvePDFJS()
const data = Deno.readFileSync('sample.pdf')
const doc = await getDocument({
data,
useSystemFonts: true,
}).promise
console.log(await doc.getMetadata())
// Iterate through each page and fetch the text content
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)
}
```
### 🌩 Cloudflare Workers
```ts
import { resolvePDFJS } from 'pdfjs-serverless'
addEventListener('fetch', (event) => {
event.respondWith(handleRequest(event.request))
})
async function handleRequest(request) {
if (request.method !== 'POST')
return new Response('Method Not Allowed', { status: 405 })
// Get the PDF file from the POST request body as a buffer
const data = await request.arrayBuffer()
// Initialize PDF.js
const { getDocument } = await resolvePDFJS()
const doc = await getDocument({
data,
useSystemFonts: true,
}).promise
// Get metadata and initialize output object
const metadata = await doc.getMetadata()
const output = {
metadata,
pages: []
}
// Iterate through each page and fetch the text content
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(' ')
// Add page content to output
output.pages.push({
pageNumber: i,
content: contents
})
}
// Return the results as JSON
return new Response(JSON.stringify(output), {
headers: { 'Content-Type': 'application/json' }
})
}
```
## How It Works
First, some string replacements of the `PDF.js` library is necessary, i.e. removing browser context references and checks like `typeof window`. Additionally, we enforce Node.js compatibility (might sound paradox at first, bear with me), i.e. mocking the `canvas` module and setting the `isNodeJS` flag to `true`.
PDF.js uses a worker to parse and work with PDF documents. This worker is a separate file that is loaded by the main library. For the serverless build, we need to inline the worker code into the main library.
To achieve the final nodeless build, [`unenv`](https://github.com/unjs/unenv) does the heavy lifting by converting Node.js specific code to be platform-agnostic. This ensures that Node.js built-in modules like `fs` are mocked.
See the [`rollup.config.ts`](./rollup.config.ts) file for more information.
## Inspiration
- [`pdf.mjs`](https://github.com/bru02/pdf.mjs), a nodeless build of PDF.js v2.
## License
[MIT](./LICENSE) License © 2023-PRESENT [Johann Schopplich](https://github.com/johannschopplich)