Untitled

<apex:page controller="ChangesetCheckerController">

<head>
   <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
</head>
<html>
<h3> Enter Change Set URL below</h3>
<div id="paraContainer" style="display:none">
    <p id="para">
        Checking on the changeset. Please wait...
    </p>
</div>
<form>
    <input id="urlInput" />
    <input id="submitbtn" type="button" value="Check Now" />
</form>
<script type="text/javascript">
    $("#submitbtn").click(function() {
        $("#paraContainer").css("display", "inline");
        checkChg();
    });

    function checkChg()
    {
        var newURL = $("#urlInput").val();
        try
        {
            Visualforce.remoting.Manager.invokeAction
            (
                '{!$RemoteAction.ChangesetCheckerController.checkChg}',
                newURL,
                function(result, event)
                {
                    var foundin = '';
                    if (event.status)
                    {
                        console.log('success');
                        console.log(result);
                        $("#para").html(result);
                        foundin = $('p:contains("Change Set Unavailable")');
                        if (result == '')
                        {
                            check();
                        }
                        else if (foundin.length == 0)
                        {
                            foundin = $('p:contains("PackageUnavailableException")');
                            if (foundin.length == 0)
                            {
                                 $("#para").empty();
                                alert('Change Set Ready');
                                window.open(newURL, "_blank");
                            }
                            else
                            {
                               check();
                            }
                        }
                    }
                    else if (event.type === 'exception')
                    {
                        console.log(event.message + " " + event.where);
                    }
                    else
                    {
                        console.log(event.message);
                    }
                },
                {
                    escape: true
                }
            );
        }
        catch (err)
        {
           check();
        }
    }
    function check()
    {
        $("#para").text("Will check in 2 seconds again.. waiting..");
        setTimeout(function() {
            $("#para").text("Checking on the changeset. Please wait...");
            checkChg();
        }, 2000);
    }
</script>

</html>

public class ChangesetCheckerController
{
@RemoteAction
public static String checkChg(String url)
{
    String html = '';
    try
    {
        PageReference page = new PageReference(url);
        Blob b = page.getContent();
        html = String.valueof(b);
        system.debug(html);
    }
    catch(Exception e)
    {
    }
    return html;
    }
}