2. To
iterate through the child nodes and disregard those text nodes, you can check the node type.
通过对子节点进行重申以及忽略这些子节点,你可以检验节点类型。
3. If you need to modify the list you are iterating over (for example, to duplicate selected items) you must
iterate over a copy.
如果你想要修改你迭代的序列(例如,复制选择项),你可以迭代它的复本。