JavaScript - Traversing a document tree

Traversing a document tree

The W3C DOM represents every document as a tree. The nodes of this tree represent the HTML tags, the strings of text, and the HTML comments that comprise the document. Each node of the tree is represented by a JavaScript object, and each has properties that allow you to traverse the tree, as illustrated by the following code fragment:

// Look up a node in the document



var n = document.getElementById("mynode");



var p = n.parentNode;  // The containing tag



var c0 = n.firstChild;    // First child of n



var c1 = c0.nextSibling;  // 2nd child of n



var c2 = n.childNodes[2]; // 3rd child of n



var last = n.lastChild;   // last child of n

See Node in the reference section for further details.

The Document object itself is a kind of node, and supports these same properties. The documentElement property of the Document object refers to the single <html> tag element at the root of all HTML documents, and the body property refers to the <body> tag.

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