Get children with tagname as only in javascript

You can simply get the #xyz div first, then find all div children:

var childDivs = document.getElementById('xyz').getElementsByTagName('div')
//                        ^ Get #xyz element;         ^ find it's `div` children.

The advantage of this method over Document.querySelectorAll is that these selectors work in pretty much every browser, as opposed to IE 8/9+ for the queryselector.