Get xml dom child element in javascript

I have an XML document like this:

<section>
   <description></description>
   <question>
       <description></description>
   </question>
</section>

I have got the sectionXML stored in a variable called SectionXML. I use:

section.description = SectionXML.getElementsByTagName("description")[0].childNodes[0];

section.description = section.description ? section.description.nodeValue : "";

However, SectionXML.getElementsByTagName("description") returns a list of many descriptions, as if we look many children deeper (great grand children etc) we can see they all have a description, but I just want to get the immediate child of SectionXML with the tag name of "description". How do I do that?