It can also save time, if it turns out (as it often does) that the only thing done with the node-set is to test whether it is empty, or to get the value of its first element.

它还可以节省时间，如果对于节点集的唯一操作就是测试它是否是空的(通常是这种情况)，或者对它的第一个元素进行赋值。

youdao

Following the quake, investigators in Yunlin county discovered that three crumbled structures had been erected by a construction company that had used empty plastic bottles and tin cans as filler to save on concrete and bricks. (The owner was arrested.) In Dali, a massive apartment block suffered major damage: one of the 11-story buildings was uprooted from the ground and fell backward.

CNN: ASIANOW - TIME Asia | Taiwan: The Day the Earth Moved--Page 3