Question

I’m trying to do AJAX on Twitter REST API (JSON Format). I did the below thing, But, nothing happens.

Not getting any response from server (Twitter). Did I miss something?

function getRecentTweet(){

        twitterUsername = document.getElementById("twitterUsername").value;

        if(window.XMLHttpRequest){
            xhr = new XMLHttpRequest();
        }
        else{
            xhr = new ActiveXObject("Microsoft.XMLHTTP");
        }

        xhr.open("GET", "http://api.twitter.com/1/statuses/user_timeline/" + twitterUsername + ".json", true);
        xhr.send(null);

        xhr.onreadystatechange = function(){
            if (xhr.readyState == 4) {
                if(xhr.status == 200) {
                    var jsonObj = eval(responseJSON);
                    document.getElementById("twitterStream").innerHTML = jsonObj[0].text;
                }
            }
        } 
    }

Thanks!

Answer 1

Yes, cross-domain AJAX calls are not allowed. You need to use JSONP.

Make a request to Twitter’s API and append the callback parameter. Here’s a sample url:

http://api.twitter.com/1/statuses/user_timeline/hulu.json?callback=myFunction

The response from Twitter then will contain executable JavaScript code with the name of the function you specified as the callback parameter. So Twitter’s response looks like:

myFunction(<JSON here>);

Since cross-domain is an issue, you need to add a script tag to the page, and set the src attribute to the above URL. This can be created and injected into the page dynamically with JavaScript.

<script src=" ... hulu.json?callback=myFunction"></script>

Then define a global function myFunction on the page that always gets called whenever the response from Twitter returns. This too can be predefined or dynamically generated.

<script>
function myFunction(data) {
    console.log(data);
}
</script>