document.createTreeWalker()

document.createTreeWalker() 方法，能创建一个 TreeWalker 对象并返回。

语法

treeWalker = document.createTreeWalker(root, whatToShow, filter, entityReferenceExpansion);

参数

root

是这个 TreeWalker 遍历的根节点(root Node)。通常这将是一个属于 document 的元素。

whatToShow 可选

它是一个无符号长整型，表示一个整合自 NodeFilter 常量属性的位掩码。对于某些类型的节点，它是一种方便的过滤方式。它默认为 0xFFFFFFFF，表示 SHOW_ALL 常量。

Constant	數值	說明
NodeFilter.SHOW_ALL	-1 (that is the max value of unsigned long)	顯示所有節點.
NodeFilter.SHOW_ATTRIBUTE	2	Shows attribute Attr nodes. This is meaningful only when creating a TreeWalker with an Attr node as its root; in this case, it means that the attribute node will appear in the first position of the iteration or traversal. Since attributes are never children of other nodes, they do not appear when traversing over the document tree.
NodeFilter.SHOW_CDATA_SECTION	8	Shows CDATASection nodes.
NodeFilter.SHOW_COMMENT	128	Shows Comment nodes.
NodeFilter.SHOW_DOCUMENT	256	Shows Document nodes.
NodeFilter.SHOW_DOCUMENT_FRAGMENT	1024	Shows DocumentFragment nodes.
NodeFilter.SHOW_DOCUMENT_TYPE	512	Shows DocumentType nodes.
NodeFilter.SHOW_ELEMENT	1	Shows Element nodes.
NodeFilter.SHOW_ENTITY	32	Shows Entity nodes. This is meaningful only when creating a TreeWalker with an Entity node as its root; in this case, it means that the Entity node will appear in the first position of the traversal. Since entities are not part of the document tree, they do not appear when traversing over the document tree.
NodeFilter.SHOW_ENTITY_REFERENCE	16	Shows EntityReference nodes.
NodeFilter.SHOW_NOTATION	2048	Shows Notation nodes. This is meaningful only when creating a TreeWalker with a Notation node as its root; in this case, it means that the Notation node will appear in the first position of the traversal. Since entities are not part of the document tree, they do not appear when traversing over the document tree.
NodeFilter.SHOW_PROCESSING_INSTRUCTION	64	Shows ProcessingInstruction nodes.
NodeFilter.SHOW_TEXT	4	顯示文字節點(Text nodes).

filter 可选

是一个可选的 NodeFilter，即一个具有 acceptNode 方法的对象，此方法被 TreeWalker 调用以决定是否接受已通过 whatToShow 检查的节点。

entityReferenceExpansion 可选

它是一个 Boolean 标识，指示当丢弃一个 EntityReference 时是否同时丢弃其子树。

示例

以下示例遍历 body 下的所有节点，将节点集合缩小至元素，简单地传递每个可接受的节点（也可在 acceptNode() 方法中缩小集合），然后利用创建的 TreeWalker 迭代器在节点上推进（现在是所有的元素）并把它们推入一个数组。

var treeWalker = document.createTreeWalker(
  document.body,
  NodeFilter.SHOW_ELEMENT,
  { acceptNode: function(node) { return NodeFilter.FILTER_ACCEPT; } },
  false
);

var nodeList = [];

while(treeWalker.nextNode()) nodeList.push(treeWalker.currentNode);

规范

浏览器兼容性

另见

• 该方法创建的对象继承的接口：TreeWalker.
• createTreeWalker on MSDN