Print PDF

print_pdf.js

/**
 * Prints a PDF in a browser using a hidden iframe. Works in recent versions of Firefox, Chrome, Safari and Edge. Does
 * not work in IE 11 and instead attempts to open the PDF in a new tab.
 *
 * Note that the PDF URL must come from the same domain as the page including this file because of the same-origin
 * policy.
 *
 * Usage: printPdf(url)
 */
var printPdf = (function() {
  // Firefox requires a delay between loading the iframe and calling print(), otherwise it fails with an uncatchable
  // error. This makes it a rare case where user agent sniffing is justified.
  var isFirefox = /Gecko\/\d/.test(navigator.userAgent);

  // Specify the aforementioned delay for Firefox. 1000 seems to work. 100 is not enough.
  var firefoxDelay = 1000;
  
  var iframe;

  return function(url) {
    // Remove iframe from any previous call
    if (iframe) {
      iframe.parentNode.removeChild(iframe);
    }

    iframe = document.createElement("iframe");
    iframe.style.cssText = "width: 1px; height: 100px; position: fixed; left: 0; top: 0; opacity: 0; border-width: 0; margin: 0; padding: 0";

    var xhr = new XMLHttpRequest();
    try {
      xhr.responseType = "arraybuffer";
    } catch (e) {
      // This is probably IE 11, in which case we can go no further and just open the PDF in a new tab
      window.open(url, "_blank");
      return;
    }

    xhr.addEventListener("load", function() {
      if (xhr.status === 200 || xhr.status === 201) {
        var pdfBlob = new Blob([xhr.response], { type: "application/pdf" });
        var iframeUrl = URL.createObjectURL(pdfBlob);
        iframe.src = iframeUrl;

        iframe.addEventListener("load", function() {
          function printIframe() {
            try {
              iframe.focus()
              try {
                iframe.contentWindow.document.execCommand("print", false, null);
              } catch (e) {
                iframe.contentWindow.print();
              }
            } catch (error) {
              console.error("Print failed: " + error, error);
            } finally {
              iframe.style.visibility = "hidden";
              iframe.style.left = "-1px";
              URL.revokeObjectURL(iframeUrl);
            }
          }

          // Add a delay for Firefox
          if (isFirefox) {
            window.setTimeout(printIframe, firefoxDelay);
          } else {
            printIframe();
          }
        });

        document.body.appendChild(iframe);
      }
    });

    xhr.open("GET", url, true);
    xhr.send();
  };
})();