Source

// pdf.js, loaded only on pages that show a document.
import * as pdfjs from "pdfjs-dist";
import workerUrl from "pdfjs-dist/build/pdf.worker.min.mjs?url";

// Start the worker as soon as a document page loads, so it is ready by the time the document's data arrives.
pdfjs.GlobalWorkerOptions.workerPort = new Worker(workerUrl, { type: "module" });

export type PdfDoc = pdfjs.PDFDocumentProxy;

export function openPdf(bytes: Uint8Array): Promise<PdfDoc> {
  // pdf.js takes ownership of the buffer it is given, so hand it a copy.
  return pdfjs.getDocument({
    data: bytes.slice(),
    isEvalSupported: false,
    // Without these, PDFs that rely on predefined character maps or standard fonts preview with blank text.
    cMapUrl: "/pdfjs/cmaps/",
    cMapPacked: true,
    standardFontDataUrl: "/pdfjs/standard_fonts/",
  }).promise;
}