js node iterator
function getChildren(parent){
//1.创建节点迭代器对象
let iterator = document.createNodeIterator(
parent, NodeFilter.SHOW_ELEMENT, null, false
);
//2.反复调用iterator的nextNode方法跳到下一个
do{
let node = iterator.nextNode();
if(node != null)
console.log(node.nodeName);
else
break;
}while(true);
}
Four kinds of query
document.getElementById()
parent.getElementsByTagName()
document.getElementsByName()
parent.getElementsByClassName()