Node、Document关系的探究

上图来自于《JavaScript权威指南(第六版)》P375

 

受到上图的启发,写了如下测试代码:

1 var head = document.getElementsByTagName("head");
2 console.log(Object.getPrototypeOf(Object.getPrototypeOf(Object.getPrototypeOf(Object.getPrototypeOf(head[0])))));    // Node对象
3 
4 console.log(Object.getPrototypeOf(Object.getPrototypeOf(Object.getPrototypeOf(document))));    // Node对象

沿着上图的文档节点层次结构,上面的代码输出都为Node对象。

 

那么问题来了,上篇博文引自《Professional JavaScript for Web Developers》中的那段话:

In browser, the document object is an instance of HTMLDocument (which inherits from Document) and presents the entire HTML page. 

1. The document object presents the entire 要怎么解释呢?(document.getElementById());   

2. Document对象和Element对象在DOM中各扮演了什么角色?(新增了哪些自己的(非继承的)属性和方法?)

 

部分解答这个问题: (《高程》P354)

  •  The Document type represents an entire document and is the root node of a hierarchy. In javaScript, the document object allows for querying and retrieval of nodes in a number of different ways.
  • An Element node represents all HTML or XML elements in a document and can be used to manipulate their contents and attributes.

 因此我们认为,首先通过Document方法找到某个节点(宏观),然后再通过手术刀式地对元素节点进行内容和属性上的操作(微观)。

 

posted @ 2015-05-21 13:38  林大勇  阅读(869)  评论(0编辑  收藏  举报