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document.createTreeWalker()
方法,能建立一個 TreeWalker
对象並傳回.
語法
treeWalker = document.createTreeWalker(root, whatToShow, filter, entityReferenceExpansion);
參數
- root
- 是這個
TreeWalker
遍歷的根節點(rootNode
). Typically this will be an element owned by the document. - whatToShow 可选
- Is an optional
unsigned long
representing a bitmask created by combining the constant properties ofNodeFilter
. 它是一種方便的方法,用來過濾某些類型的節點。 It defaults to0xFFFFFFFF
representing theSHOW_ALL
constant.Constant 數值 說明 NodeFilter.SHOW_ALL
-1
(that is the max value ofunsigned long
)顯示所有節點. NodeFilter.
SHOW_ATTRIBUTE2
Shows attribute Attr
nodes. This is meaningful only when creating aTreeWalker
with anAttr
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_SECTION8
Shows CDATASection
nodes.NodeFilter.
SHOW_COMMENT128
Shows Comment
nodes.NodeFilter.
SHOW_DOCUMENT256
Shows Document
nodes.NodeFilter.
SHOW_DOCUMENT_FRAGMENT1024
Shows DocumentFragment
nodes.NodeFilter.
SHOW_DOCUMENT_TYPE512
Shows DocumentType
nodes.NodeFilter.
SHOW_ELEMENT1
Shows Element
nodes.NodeFilter.
SHOW_ENTITY32
Shows Entity
nodes. This is meaningful only when creating aTreeWalker
with anEntity
node as its root; in this case, it means that theEntity
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_REFERENCE16
Shows EntityReference
nodes.
SHOW_NOTATIONNodeFilter.
2048
Shows Notation
nodes. This is meaningful only when creating aTreeWalker
with aNotation
node as its root; in this case, it means that theNotation
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_INSTRUCTION64
Shows ProcessingInstruction
nodes.NodeFilter.
SHOW_TEXT4
顯示文字節點( Text
nodes). - filter 可选
- 是一個可選的
NodeFilter
, 這是一個对象有著acceptNode
方法, 這方法被TreeWalker
呼叫來決定是否接受通過whatToShow
檢查的節點. - entityReferenceExpansion 可选
- Is a
Boolean
flag indicating if when discarding anEntityReference
its whole sub-tree must be discarded at the same time.
示例
The following example goes through all nodes in the body, reduces the set of nodes to elements, simply passes through as acceptable each node (it could reduce the set in the acceptNode()
method instead), and then makes use of tree walker iterator that is created to advance through the nodes (now all elements) and push them into an array.
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
规范 | 状态 | 备注 |
---|---|---|
DOM Document.createTreeWalker |
Living Standard | Removed the expandEntityReferences parameter.Made the whatToShow and filter parameters optionals. |
Document Object Model (DOM) Level 2 Traversal and Range Specification Document.createTreeWalker |
Recommendation | Initial definition. |
浏览器兼容性
功能 | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
基础支持 | 1.0 | 2.0 (1.8.1) | 9.0 | 9.0 | 3.0 |
whatToShow and filter optional |
1.0 | 12 (12) | 未实现 | (Yes) | 3.0 |
expandEntityReferences |
1.0 | 2.0 (1.8.1) 于12 (12)移除 |
9.0 | 9.0 | 3.0 |
功能 | Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|
基础支持 | (Yes) | 1.0 (1.8.1) | (Yes) | 9.0 | 3.0 |
whatToShow and filter optional |
(Yes) | 12 (12) | 未实现 | (Yes) | 3.0 |
expandEntityReferences |
(Yes) | 2.0 (1.8.1) 于12 (12)移除 |
(Yes) | 9.0 | 3.0 |
另见
- The interface of the object it creates:
TreeWalker
. - createTreeWalker on MSDN