A live collection of an element's (or a document's / document fragment's) element children: it is not a snapshot, reading it after the tree changes reflects the change.
How many elements are in the collection.
The element at the given index, or null when there is none.
The element whose id, or whose name attribute, is the given value, or null when there is none.
A live collection of an element's (or a document's / document fragment's) element children: it is not a snapshot, reading it after the tree changes reflects the change.