Change Master page of a site using ECMA Script in sharepoint 2010

Hi All,

I'm working on SharePoint 2010.

I have a requirement where in I need to create a site and apply a particular master page to the newly created site usingECMA Script.

The site gets created but while applying the master page it gives me an error stating the method 'set_masterUrl' is not defined.

Here is my code:

$(document).ready(function () {
    ExecuteOrDelayUntilScriptLoaded(createSite, "sp.js"); //This is used to ensure until sp.js is loaded, createSite will not be executed.
});


function createSite() {
    var context = SP.ClientContext.get_current();
    var collWeb = context.get_web().get_webs();
    var webCreationInfo = new SP.WebCreationInformation();
    webCreationInfo.set_title('TestSite');
    webCreationInfo.set_description('Description of new Web site...');
    webCreationInfo.set_language(1033);
    webCreationInfo.set_webTemplate('STS#0');
    webCreationInfo.set_url('TestSite');
    webCreationInfo.set_useSamePermissionsAsParentSite(false);

    var oNewWebsite = collWeb.add(webCreationInfo);
    
    context.load(oNewWebsite);
    context.executeQueryAsync(Onsuccess, onfail);
    function Onsuccess() {
        dummy(context, oNewWebsite);
    }
    function onfail(sender, args) {
        alert('Request failed. ' + args.get_message() + '\n' + args.get_stackTrace());
    }

}
function dummy(context,oNewWebsite)
{
    var strMasterPageUrl = '/_catalogs/masterpage/Test.master';
    oNewWebsite.set_masterUrl(strMasterPageUrl);
    oNewWebsite.set_customMasterUrl(strMasterPageUrl);

    oNewWebsite.update();
    context.executeQueryAsync(Onsuccess1, onfail1);
    function Onsuccess1() {
        alert("Done");
    }
    function onfail1(sender, args) {
        alert('Request failed. ' + args.get_message() + '\n' + args.get_stackTrace());
    }

}

Please help.

Thanks,

Sachin