AJAX Permission Denied On IE?

问题

I'm trying to make an ajax call to an external domain that is already allowing external requests by sending Access-Control-Allow-Origin:* header, but i get Permission Denied on the xmlhttp.post() line.

Here is my code:

var xmlhttp;
try {
    xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
    try {
        xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
    } catch (E) {
        xmlhttp = false;
    }
}

if (!xmlhttp && typeof XMLHttpRequest != 'undefined') {
    try {
        xmlhttp = new XMLHttpRequest();
    } catch (e) {
        xmlhttp = false;
    }
}

xmlhttp.onreadystatechange = function () {
    if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
        alert(xmlhttp.responseText);
    }
}

xmlhttp.open("GET", "http://www.domain.com", true);
xmlhttp.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
xmlhttp.send();

回答1:

I believe that in IE, you still can't use XMLHttpRequest for cross domain requests. For that, you need to use XDomainRequest object. Full documentation is here. I believe the reason for introducing the separate object was to allow developers to do a compatibility test before making a request that certainly would fail with older browsers.

回答2:

I believe you can only use Ajax with URL's form the same domain as your calling page. It's not the external domain that disallows the request, it's your browser's security. Take a look at Same Origin Policy This is a way to avoid cross browser scripts - otherwise imagine you have a page where you can enter your credit card info and someone injects a script that sends information you are typing to an external site. Would be a big problem to fight.

回答3:

Note :Do not use "http://domain.xxx" or "http://localhost/" or "IP" for URL in Ajax. Only use path(directory) and page name without address.

false state:

var AJAXobj = createAjax();
AJAXobj.onreadystatechange = handlesAJAXcheck;
AJAXobj.open('POST', 'http://www.example.com/dir1/dir2/page.php', true);
AJAXobj.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8');
AJAXobj.send(pack);

true state:

var AJAXobj = createAjax();
AJAXobj.onreadystatechange = handlesAJAXcheck;
AJAXobj.open('POST','dir1/dir2/page.php', true);   // <<--- note
AJAXobj.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8');
AJAXobj.send(pack);

---

function createAjax()
{
    var ajaxHttp = null;
    try
    {
        if(typeof ActiveXObject == 'function')
            ajaxHttp = new ActiveXObject("Microsoft.XMLHTTP");
        else 
        if(window.XMLHttpRequest)
            ajaxHttp = new XMLHttpRequest();
    }
    catch(e)
    {
        alert(e.message);
        return null;
    }
    //-------------
    return ajaxHttp;
};

来源：https://stackoverflow.com/questions/4772019/ajax-permission-denied-on-ie