The are two divs on this page. One is called file1. The second div is called file2. The makeRequest javascript function creates an XMLHttpRequest object and updates the file1 & file2 divs. The file2 div is not updated. There appears to be a parsing bug in the Firefox xml parser. Firefox cannot process a space between a CDATA tag and a previous tag. You should see a "from file2.xml." The file2.xml file contains one space between the <html> tag and <![CDATA[ tag.