2023-08-15T13:54:49.png

输出整个文档

2023-08-15T13:56:20.png

   console.log(document);

2023-08-15T13:58:40.png

2023-08-15T13:59:01.png

   if(document.nodeType === 9){
    console.log("顶层节点");

   };