How would I use jQuery to grab the contents of a page and render it within a div

function render_message(id)
{
var xmlHttp;
  xmlHttp=new XMLHttpRequest();
  xmlHttp.onreadystatechange=function()
    {
    if(xmlHttp.readyState==4)
      {
        document.getElementById('message').innerHTML=xmlHttp.responseText;
        document.getElementById('message').style.display='';
        }
    }
    var url="include/javascript/message.php";
    url=url+"?q="+id;
  xmlHttp.open("GET",url,true);
  xmlHttp.send(null);
}

$('#message').load("include/javascript/message.php", {q: id}, function() {
    $(this).show();
});

$("#mydiv").load("a/url/here.html");