Amazon S3 upload via Iframes

Question

Sigh, we\'re back to this. I can easily enough use CORS on any decent enough browser to directly upload files to my AWS S3 bucket. But (it was coming), with IE I have to fall ba

Answer 1

AS for the "postMessage" scenario, maybe the iframe should contain a simple javascript

[edit] for iframes taken over by an errormessage

IFRAME script

window.document.onload = function(e){ 
    window.parent.postMessage(document, '*'); //replace '*' with your parent if possible   
}
// just to get the proper document for the parent to target me
window.addEventListener('message',function(e) {
    if (e.domain == 'example.com') { // the domain of your parent frame
        if (e.data == "Salute") {
            window.parent.postMessage("I'm here", '*'); //replace '*' with your parent too
        }
    }
});

Now parent knows the iFrame perfectly well and can track it's status (depending on if it's answering a simple postMessage)

PARENT script

var iFrameTarget;
var iFrameTakenOver = false;
var timer;
window.addEventListener('message',function(e) {
    if (e.domain == 'example.com') { // the domain of your iframe
        if (e.data) { // e.data contains the iframe document
            if(typeof(e.data) =='object')
                iFrameTarget = e.source;
            elseif(e.data == "I'm here")
            {
                iFrameTakenOver = false;
            }
            timer =setInterval(call_iFrame(),5000); // check iFrame presence in 5 seconds
        }
    }
});

function call_iFrame() {
    iFrameTarget.postMessage('Salute');
    iFrameTakenOver = true;
}

IF iframe is not responding with it's "code" iFrameTakenOver will be permanently set to false checking that will verify if an error has occured or not.