observe method
Registers a node to observe and specifies the change information to record.
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Syntax
MutationObserver.observe(target, options);Parameters
- target [in]
-
Type: Node
The DOM node to observe.
- options [in]
-
Type: MutationObserverInit
The default value of all properties is false unless otherwise specified.
Value Meaning - childList
Set to true to monitor additions and removals of the target node's child elements. This option includes text nodes that are added or removed as children of the target element. Example:
{ childList: true }
- attributes
Set to true to monitor changes (additions, removals, and changes in values) to the target node's attributes. Example:
{ attributes: true }
- characterData
Set to true to monitor changes to the value of the target node's text content (child text nodes). Example:
{ characterData: true }
- subtree
Set to true to also monitor changes to all of the target node's descendants (childList, attributes, or characterData must also be true). Example:
{ childList: true, subtree: true }
- attributeOldValue
Set to true to record the target node's previous attribute value (attributes must also be true). Example:
{ attributes: true, attributeOldValue: true }
- characterDataOldValue
Set to true to record the target node's previous text data (characterData must also be true). Example:
{ characterData: true, characterDataOldValue: true }
- attributeFilter
Set to an array of attribute local names (without namespace) to only monitor changes to specific attributes (attributes must also be true). Example:
{ attributes: true, attributeFilter: ["id", "dir"] }
Return value
This method does not return a value.
Remarks
The attributes, childList, characterData options will by default only observe the target element in isolation, not considering any of its descendants. In order to cause the observer to watch the given element and all of its children, the subtree option must also be set to true.
See also