var xhr = new XMLHttpRequest; xhr.onerror = function () { postMessage("xhr blocked"); postMessage("TEST COMPLETE"); }; xhr.onload = function () { //cons/**/ole.log(xhr.responseText); if (xhr.responseText == "FAIL") { postMessage("xhr allowed"); } else { postMessage("xhr blocked"); } postMessage("TEST COMPLETE"); }; try { xhr.open("GET", "/common/redirect.py?location=http://{{host}}:{{ports[http][0]}}/content-security-policy/support/fail.asis", true); xhr.send(); } catch (e) { postMessage("xhr blocked"); postMessage("TEST COMPLETE"); }