问Wikipedia API+跨源请求

EN

var WikipediaCORS=
    {
    setMessage:function(msg)
        {
        var span=document.getElementById("id1");
        span.appendChild(document.createTextNode(msg));
        },
    // Create the XHR object.
    createCORSRequest:function(url)
        {
        var xhr = new XMLHttpRequest();


        if ("withCredentials" in xhr)
            {
            xhr.open("GET", url, true);
            }
        else if (typeof XDomainRequest != "undefined")
            {
            xhr = new XDomainRequest();
            xhr.open(method, url);
            }
        else
            {
            return null;
            }
        xhr.setRequestHeader("Access-Control-Allow-Credentials", "true");
        xhr.setRequestHeader("Access-Control-Allow-Origin","*");
        return xhr;
        },
    init:function()
        {
        var _this=this;
        var url = 'http://en.wikipedia.org/w/api.php?action=opensearch&search=Javascript&format=json';
        var xhr = this.createCORSRequest(url);
        if (!xhr)
            {
                this.setMessage('CORS not supported');
                return;
            }

        xhr.onload = function()
            {
                _this.setMessage(xhr.responseText);
            };
        xhr.onerror = function()
            {
                _this.setMessage('Woops, there was an error making the request.');
            };
        xhr.send();
        }
    };