Defer javascript and asynchronous loading of social plugin

<!-- FB code for asynchronous loading -->
<script type="text/javascript">
    // prevent jQuery from appending cache busting string to the end of the FeatureLoader URL
    var cache = jQuery.ajaxSettings.cache;
    jQuery.ajaxSettings.cache = true;
    // Load FeatureLoader asynchronously. Once loaded, we execute Facebook init
    jQuery.getScript('http://connect.facebook.net/en_US/all.js', function() {
    FB.init({appId: 'your-app-id', status: true, cookie: true, xfbml: true});
    });
    // just Restore jQuery caching setting
    jQuery.ajaxSettings.cache = cache;
    </script>


<!-- Gplus button asynchronous loading -->
<script type="text/javascript">
  (function() {
    var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true;
    po.src = 'https://apis.google.com/js/plusone.js';
    var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s);
  })();
</script>


<!-- Gplus button defer script -->
<script defer="defer" type="text/javascript">
    window.onload=function(){
        var mycode;
        mycode=document.createElement("script");
        mycode.type="text/javascript";
        mycode.src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js";
        document.getElementsByTagName("head")[0].appendChild(mycode);
    }
</script>