pdfjs の使い方

<script src="//mozilla.github.io/pdf.js/build/pdf.js"></script>

<h1>PDF.js 'Hello, world!' example</h1>

<canvas id="the-canvas"></canvas>

var url =
  "https://raw.githubusercontent.com/mozilla/pdf.js/ba2edeae/examples/learning/helloworld.pdf";

// Loaded via <script> tag, create shortcut to access PDF.js exports.
var pdfjsLib = window["pdfjs-dist/build/pdf"];

// The workerSrc property shall be specified.
pdfjsLib.GlobalWorkerOptions.workerSrc =
  "//mozilla.github.io/pdf.js/build/pdf.worker.js";

// Asynchronous download of PDF
var loadingTask = pdfjsLib.getDocument(url);
loadingTask.promise.then(
  function (pdf) {
    console.log("PDF loaded");

    // Fetch the first page
    var pageNumber = 1;
    pdf.getPage(pageNumber).then(function (page) {
      console.log("Page loaded");

      var scale = 1.5;
      var viewport = page.getViewport({ scale: scale });

      var canvas = document.getElementById("the-canvas");
      var context = canvas.getContext("2d");
      canvas.height = viewport.height;
      canvas.width = viewport.width;

      // Render PDF page into canvas context
      var renderContext = {
        canvasContext: context,
        viewport: viewport,
      };
      var renderTask = page.render(renderContext);
      renderTask.promise.then(function () {
        console.log("Page rendered");
      });
    });
  },
  function (reason) {
    // PDF loading error
    console.error(reason);
  }
);