Question: I'm working on a Drupal 6 module where I use jquery (and more specifically, the $.ajax method) to retrieve a RSS feed from Yahoo's weather API. I decided against using the JFeed library because I need access to the elements with "yweather" prefix (and I couldn't find a way of accessing them via JFeed). I decided to use the $.ajax method and parse the XML response instead. The JavaScript code below works fine in Firefox and IE but does not work in Safari (or Chrome FWIW):

```
function parseXml(xml) {
  var atmosphere = xml.getElementsByTagName("yweather:atmosphere");

  var humidity = atmosphere[0].getAttribute("humidity");

  $('#weatherFeed').html("Humidity: " + humidity);
  $('#weatherFeed').append(
     "<div style=\"text-align: center;margin-left: auto; margin-right: auto;\">" + 
     city + ", " + state + "</div>");
}

function getData(){
   $.ajax({
      type:   'GET',
      url:    'proxy.php?url=http://weather.yahooapis.com/forecastrss&p=94041',
      dataType: 'xml',
      success:  function(xml) {
      parseXml(xml);
 }
 }); 
}

if(Drupal.jsEnabled) {
$(function() {
      getData();
      setInterval("getData()", 30000);
      });   
}

```

When I check the error console in Safari I see the following error message: `TypeError: Result of expression 'atmosphere[0]' [undefined] is not an object.` Is there an issue with using getElementsByTagName in Safari? Should I be accessing the object that's returned by getElementsByTagName differently?

Answer: 
I had the exact same problem, but came across the answer here: 
<http://reference.sitepoint.com/javascript/Document/getElementsByTagName>

It has to do with the yweather namespace. Use getElementByTagNameNS function instead.

`var atmosphere = xml.getElementsByTagName("yweather:atmosphere");`

becomes

`var atmosphere = xml.getElementsByTagNameNS("http://xml.weather.yahoo.com/ns/rss/1.0","atmosphere");`

function reference:
<http://reference.sitepoint.com/javascript/Document/getElementsByTagNameNS>
Have you tried atmosphere[1] instead of 0 for Chrome and Safari?