Can't read JSON response from server

Question

I am working on a web app that sends some data to a website. The website updates the data to its database and returns a json array that replaces my webapp page. I am using ajax for making the query. I need to know how to prevent the overwriting of my webpage. The server is not mine so there is possibly a same origin policy problem.
I have checked the xmlhttp.readystate and xmlhttp.status, they are 4 and 0 respectively. According to some posts on stackoverflow the 0 status occurs due to the origin policy but I couldn't get a solution for this because usually the people with this problem had access to changes on the server side programming.
I want to read the json and extract values for my app but if I use the xmlhttp.responseText the server returns a blank string.

Any help is much appreciated.
Thanks

My code:

function sendAndReceive() {

    var xmlhttp;
    xmlhttp = new XMLHttpRequest();

    xmlhttp.onreadystatechange = function () {
        document.getElementById("postevent").innerHTML = "state changed";
        document.getElementById("postevent").innerHTML = "" + xmlhttp.readyState + " " + xmlhttp.status;
        if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
            document.getElementById("postevent").innerHTML = "success response";
            document.getElementById("postevent").innerHTML = "this is it" + xmlhttp.responseText;
        }
    }

    var url = "http://simple.ap.ernet.in/api/home/resource.php/resource/node?";
    url += "key=" + document.getElementById("key").value + "&";
    url += "datasetId=" + document.getElementById("datasetId").value + "&";
    url += "localId=" + document.getElementById("localId").value + "&";
    url += "nodeName=" + document.getElementById("nodeName").value + "&";
    url += "nodeDesc=" + document.getElementById("nodeDesc").value + "&";
    url += "lat=" + document.getElementById("lat").value + "&";
    url += "long=" + document.getElementById("long").value;

    document.getElementById("postevent").innerHTML = url;
    xmlhttp.open("POST", url, true);
    xmlhttp.send();
}

I don't get your question : you know you can't do it because of same origin policy so what are you asking exactly ? — Denys Séguret, Dec 20 '12 at 07:30
I am asking if there is a workaround to this because i felt i shouldn't be the only one doing this for the first time. — user1900588, Dec 20 '12 at 07:31

score 1 · Answer 1 · edited May 23 '17 at 11:43

1

The only known workaround is to let the browser think there is only one origin. The easiest is to put a proxy on your own server relaying to the other server. If your own server is in Apache, you may use mod_proxy (see this question).

But note that if the other server doesn't allow cross-origin requests, it's probably against its policy to do that. And if it's a big server, it may very well detect it and ban your server's IP.

edited May 23 '17 at 11:43

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answered Dec 20 '12 at 07:33

Denys Séguret

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I read about the mod_proxy and other questions already. I couldn't find anything that could solve my problem. The workarounds worked around apache so no use for me. – user1900588 Dec 20 '12 at 07:43

Can't read JSON response from server

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