跨域-适应ajax跨域

Question

是否可以将此代码用于跨域，以及如何

function makeRequest(url) {
    var http_request = false;
    if (window.XMLHttpRequest) { // Mozilla, Safari,...
        http_request = new XMLHttpRequest();
        if (http_request.overrideMimeType) {
                http_request.overrideMimeType('text/xml');
        }
    } else if (window.ActiveXObject) { // IE
        try {
            http_request = new ActiveXObject("Msxml2.XMLHTTP");
        } catch (e) {
            try {
            http_request = new ActiveXObject("Microsoft.XMLHTTP");
            } catch (e) {}
        }
    }
    if (!http_request) {
        alert('Cannot create an XMLHTTP instance');
        return false;
    }
    http_request.onreadystatechange = function() { alertContents(http_request); };
    http_request.open('GET', url, true);
    http_request.send(null);
}
function alertContents(http_request) {
    if (http_request.readyState == 4) {
        if (http_request.status == 200) {
            receiveData(http_request.responseText);
        } else {
            alert("Îòâåò ñåðâåðà ïîëó÷åí, íî åñòü îøèáêà");
        }         
    } 
}

Answer 1

在正常情况下，同源策略防止JavaScript读取来自不同源的数据。

你可以使用:

1. 页面源数据的代理
2. JSONP
3. CORS(浏览器支持有限，但现在可能已经足够好了)