How to handle cross domain?

[pendave]

I try to use Greasemonkey GM_xmlhttpRequest but responseType : "arraybuffer" is not supported.

[pendave]

I try to rip out the email info from online PDF and firstly the whole text should be get.

So I find http://hublog.hubmed.org/archives/001948.html
and its nice example:
http://git.macropus.org/2011/11/pdftotext/example

I use Greasemonkey version 4.1.10 to do a cross domain version with GM_xmlhttpRequest.
I see responseType : "arraybuffer" should be working but I can't get the script doing right from XMLHttpRequest to GM_xmlhttpRequest.

Here's the script from that site, how can I make it working correctly?
var pdfsrc = window.location.href;
//using a sample PDF for test now
pdfsrc ='http://git.macropus.org/2011/11/pdftotext/example/journal.pone.0026738.pdf';
html = document.body.innerHTML +'<div style="position: absolute; left: 10px; top: 200px; color: white; z-index: 100;">Attention<br><iframe id="input" src="'+ pdfsrc +'"></iframe><br><iframe id="processor" src="http://hubgit.github.com/2011/11/pdftotext/"></iframe><br><div id="output"></div></div>';
document.body.innerHTML = html;
//document.getElementById("plugin").remove();
var input = document.getElementById("input");
var processor = document.getElementById("processor");
var output = document.getElementById("output");
// listen for messages from the processor
window.addEventListener("message", function(event){
if (event.source != processor.contentWindow) return;
switch (event.data){
// "ready" = the processor is ready, so fetch the PDF file
case "ready":
var xhr = new XMLHttpRequest();
//url: input.getAttribute("src"),
url: pdfsrc,
xhr.responseType = "arraybuffer";
xhr.onload = function(event) {
processor.contentWindow.postMessage(this.response, "*");
};
xhr.send();
break;
// anything else is the text of the PDF
default:
output.textContent = event.data.replace(/\s+/g, " ");
break;
}
}, true);

Especially here I update with

case "ready":
GM_xmlhttpRequest({
method: "GET",
url: input.getAttribute("src"),
onload: function(event) {
processor.contentWindow.postMessage(this.response, "*");
}
});
break;