Could not be cloned

[KTPenrose]

I unfortunately can't upload the PDF because I don't have authorization to do so in my massive bureaucracy.

Web browser: Chrome 58.0.3029.110 (64-bit)
Windows 10
PDF.js version 1.8.188 (although main fails as well)

Background; I am using the library to extract the contents of form fields (getAnnotations()), and NOT to display the document in the browser. The gist of the problem is that a call to page.getAnnotation() fails when there is a form field (such as in my case a signature block) that can't be serialized. It throws an exception deep in util.js and abandons the whole call to page.getAnnotation() as below;

:8888/src/shared/util.js:1301 

Uncaught (in promise) DataCloneError: Failed to execute 'postMessage' on 'DedicatedWorkerGlobalScope': function NetworkManager_getXhr() {
		return new XMLHttpRequest();
	  } could not be cloned.

I tried catching the exception in my code by wrapping the call to page.getAnnotations() in a try catch, but it doesn't seem to work. It does work to comment out that block of code.

If someone could tell me how to just ignore problematic fields/annotations this would be a wonderful solution.

'use strict';

// In production, the bundled pdf.js shall be used instead of SystemJS.
Promise.all([SystemJS.import('pdfjs/display/api'),
			 SystemJS.import('pdfjs/display/global')])
	   .then(function (modules) {
  var api = modules[0], global = modules[1];
  // In production, change this to point to the built `pdf.worker.js` file.
  global.PDFJS.verbosity=global.PDFJS.VERBOSITY_LEVELS.infos;
  global.PDFJS.workerSrc = '../../src/worker_loader.js';

  // Fetch the PDF document from the URL using promises.
  api.getDocument('myDocument.pdf').then(function (pdf) {
	// Fetch the page.
	var numPages = pdf.numPages;
	var myResult="";
	function myCallback(pageNumber, text) {
		//alert("processing page "+pageNumber+", text="+text);
		document.getElementById("myFormDiv").innerHTML+=text;
	}
	for (var pageNum = 1; pageNum<=numPages; pageNum++) {
		function doit(currentPageNumber) {
			//alert("processing page "+currentPageNumber);
			var response="<h1>Page "+currentPageNumber+"</h1>\n";
			pdf.getPage(currentPageNumber).then(function (page) {
					  
				function escapeHtml(unsafe) {
					if (typeof unsafe !== 'string') { return ""; }
					return unsafe.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;").replace(/"/g, "&quot;").replace(/'/g, "&#039;");
				}

				//attempt to read the data!!!!
				page.getAnnotations().then(function(items) {
					console.log(items); //Dump this into the console to see what properties are available for each field				
					items.forEach(function(item) {
						response+="<div>"+escapeHtml(item.alternativeText)+":"+escapeHtml(item.fieldValue)+"<div>\n";
					});
					myCallback(currentPageNumber, response);			
				}); //end getAnnotations()
					
			}); //end getPage()
			
			return response;
		} //end doit()
		doit(pageNum);
	}//end iterating pages
  }); //end getDocument()
});

[KTPenrose]

Problem solved with the following added line... I just had to state my intention.

			var parameters = { intent: 'display' };
			page.getAnnotations(parameters).then(function(items) {