javascript - Wikipedia API + Cross-origin requests

Question

I'm trying to access Wikipedia using JavaScript and CORS.

As far as I know, Wikipedia should support CORS: http://www.mediawiki.org/wiki/API:Cross-site_requests

I tried the following script: create a XMLHttpRequest+credential/XDomainRequest, add some HTTP headers ("Access-Control-Allow-Credentials", etc.) and send the query.

http://jsfiddle.net/lindenb/Vr7RS/

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();
        }
    };

But my script fails ('xhr.onerror' is called). How can I fix it?

Answer 1

I had the same problem while working on a freeCodeCamp project and the solution was so simple it made me laugh, since I had spent hours searching for it. In your jQuery URL include the parameter below.

&origin=*

Working CodePen

$.getJSON(
  'https://en.wikipedia.org/w/api.php?action=query&format=json&gsrlimit=15&generator=search' +
  '&origin=*' + // <-- this is the magic ingredient!
  '&gsrsearch='q, function(data){ /* ... */ }
);