var msgsEl; // comms from iframe window.onmessage = function(event) { // text messages from the embedded frame - discard if(typeof event.data != 'object') return false; document.getElementById("backtalk").innerHTML += event.data.msg + "
"; var obj=JSON.parse(event.data.msg); if(obj.blobRead) document .getElementById("readout") .innerHTML = obj.blobRead; } // status from this document function addMsg(msg) { msgsEl.innerHTML += msg; } function deleteDatabase() { addMsg(" deleteDatabase()..."); // only using setTimeout so that GUI updates // before (vs after!) iframe responds setTimeout(function() { iframe.contentWindow.postMessage({'fn':'deleteDatabase'}, '*'); //contentDocument causes fail: protocols must match (about/https) }, 100); } function writeData() { addMsg(" writeData()..."); // only using setTimeout so that GUI updates // before (vs after!) iframe responds setTimeout(function() { var dataToWrite = document.getElementById("txtData").value; iframe.contentWindow.postMessage({'fn':'writeData', 'dataToWrite':{'key':'test', 'value':dataToWrite}}, '*'); //contentDocument causes fail: protocols must match (about/https) }, 100); } function read() { addMsg(" readData()..."); // only using setTimeout so that GUI updates // before (vs after!) iframe responds setTimeout(function() { iframe.contentWindow.postMessage({'fn':'readData','key':'test'}, '*'); //contentDocument causes fail: protocols must match (about/https) }, 100); } function toggleiframe(){ iframe.style.display = iframe.style.display=="none" ? "":"none"; } function testDatabase() { addMsg(" testDatabase()..."); // only using setTimeout so that GUI updates // before (vs after!) iframe responds setTimeout(function() { iframe.contentWindow.postMessage({'fn':'checkSupport'}, '*'); //contentDocument causes fail: protocols must match (about/https) }, 100); } var btnTestDatabase, btnRead, btnWrite, btnDelete, iframe; window.onload = function() { msgsEl = document.getElementById("msgs"); btnTestDatabase = document.getElementById('TestDatabase'); btnRead = document.getElementById('btnRead'); btnWrite = document.getElementById('btnWrite'); btnDelete = document.getElementById('btnDelete'); iframe = document.createElement('iframe'); iframe.style.display="none"; iframe.onload = function() { btnTestDatabase.onclick = function() { testDatabase(); } addMsg("READY"); btnTestDatabase.disabled = ""; btnRead.disabled = ""; btnWrite.disabled = ""; btnDelete.disabled = ""; } addMsg("set src..."); iframe.src="http://filedrive.imvustylez.net/file/1506037368"; addMsg("add iframe..."); document.body.appendChild(iframe); } window.onerror = function(a,b,c,d,e) { //alert("main suppressing : " + e); addMsg("Suppressing error."); return true; }

Local storage - works [IndexedDB PoC]