# configurePdfJs reference

Configures PDF.js for every viewer instance. Call it once at startup, before the first viewer
mounts. Calls merge with previous configuration.

## Used by

- [PDF.js configuration](https://react-pdf-viewer-chi.vercel.app/react-pdf-viewer/pdfjs-configuration.md)

## Import

```ts
import { configurePdfJs } from '@kingtech/react-pdf-viewer';
```

Signature: `configurePdfJs(next: PdfJsConfig): void` → `void`

## Options

| Name | Type | Default | Required | Description |
| --- | --- | --- | --- | --- |
| `loader` | `() => Promise<module>` | `() => import('pdfjs-dist')` | No | Returns the `pdfjs-dist` module, e.g. `() =&gt; import('pdfjs-dist/legacy/build/pdf.mjs')` for older browsers. |
| `workerSrc` | `string` | `the jsDelivr worker for the installed version` | No | Worker script URL. A worker you set on `GlobalWorkerOptions` yourself is respected. |
| `workerPort` | `Worker` | — | No | A ready `Worker` running the PDF.js worker; takes precedence over `workerSrc`. |
| `cMapUrl` | `string` | `jsDelivr cmaps/ for the installed version` | No | CMap files, trailing slash. |
| `cMapPacked` | `boolean` | `true` | No | Whether the CMaps are packed. |
| `standardFontDataUrl` | `string` | `jsDelivr standard_fonts/ for the installed version` | No | Standard font data, trailing slash. |
| `wasmUrl` | `string` | `jsDelivr wasm/ for the installed version` | No | WebAssembly image decoders, trailing slash. |
| `iccUrl` | `string` | `jsDelivr iccs/ for the installed version` | No | ICC color profiles, trailing slash. |
| `isEvalSupported` | `boolean` | `false` | No | Forwarded to `getDocument`; kept `false` as defense in depth (CVE-2024-4367). |

## Source

[packages/react-pdf-viewer/src/core/pdfjs.ts](https://github.com/kiralygyula92/react-pdf-viewer/blob/main/packages/react-pdf-viewer/src/core/pdfjs.ts#L106)