Don't get me wrong, it's great that @calixteman wanted to implement that — JS should definitely be supported! I don't want to come off as rude or attacking.

For starters, JS reference specified in the [commit comment](https://github.com/mozilla/pdf.js/commit/8de98079ca05f8f7001ee077771055a57dc0e948) is outdated. It's version 8.1 from 2007… We're more than decade past that now. We should be implementing [Acrobat DC SDK](https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/AcrobatDC_js_api_reference.pdf) ([here](https://help.adobe.com/en_US/acrobat/acrobat_dc_sdk/2015/HTMLHelp/#t=Acro12_MasterBook%2FJS_API_AcroJS%2FJavaScript_API.htm) in a nice HTML version).

Other than that, the Doc object now is only implemented with `info` property with standard fields (`Title`, `Author`, `Subject`, `Keywords`, `Creator`, `Producer`, `CreationDate`, `ModDate` and `Trapped`, case insensitive). But [according to the spec](https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/AcrobatDC_js_api_reference.pdf#page=243) (even [in that old version](https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/js_api_reference.pdf#page=243)), this object can contain other, non-standard properties, that can be set both in Acrobat interface and in JS (which are case-sensitive then).

Acrobat 9.0 introduced another field to that property, `Authors`, containing semicolon-delimited list of authors.

There are probably other problems with that code due to the outdated spec @calixteman was apparently working on.
if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC || CHROME")) {
    const { eventBus } = PDFViewerApplication;
    
    if (cmd === 1 || cmd === 8) {
      switch (evt.keyCode) {
        case 83: 
          eventBus.dispatch("download", { source: window });
          handled = true;
          break;
        case 79: 
          if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
            eventBus.dispatch("openfile", { source: window });
            handled = true;
          }
          break;
      }
    }
  }
  
  if (cmd === 3 || cmd === 10) {
    switch (evt.keyCode) {
      case 80: 
        PDFViewerApplication.requestPresentationMode();
        handled = true;
        break;
      case 71: 
        
        PDFViewerApplication.appConfig.toolbar.pageNumber.select();
        handled = true;
        break;