MutationObserverInit
dictionary's optional
属性
property is used to specify whether or not to watch for attribute value changes on the node or nodes being observed.
var options = {
attributes: true | false
}
A Boolean value indicating whether or not to report through the callback any changes to the values of attributes on the node or nodes being monitored. The default value is
false
.
若
true
, the callback specified when
observe()
was used to start observing the node or subtree will be called any time one or more attributes have changed on observed nodes.
You can expand the capabilities of attribute mutation monitoring using other options:
attributeFilter
lets you specify specific attribute names to monitor instead of monitoring all attributes.
attributeOldValue
lets you specify whether or not you want the previous value of changed attributes to be included in the
MutationRecord
's
oldValue
特性。
subtree
lets you specify whether to watch the target node and all of its descendants (
true
), or just the target node (
false
).
If you set either
attributeFilter
or
attributeOldValue
to
true
,
属性
is automatically assumed to be
true
, even if you don't expressly set it as such.
In this example, a Mutation Observer is set up to watch for changes to the
status
and
username
attributes in any elements contained within a subtree that displays the names of users in a chat room. This lets the code, for example, reflect changes to users' nicknames, or to mark them as away from keyboard (AFK) or offline.
function callback(mutationList) {
mutationList.forEach(function(mutation) {
switch(mutation.type) {
case "attributes":
notifyUser("Attribute name " + mutation.attributeName +
" changed to " + mutation.target[mutation.attributeName] +
" (was " + mutation.oldValue + ")");
break;
}
});
}
var targetNode = document.querySelector("#target");
var observer = new MutationObserver(callback);
observer.observe(targetNode, {
attributes: true,
attributeOldValue: true
});
callback()
function—which will be passed into the
observe()
method when starting the observer, looks at each item in the list of
MutationRecord
objects. For any items representing an attribute change (which can be detected by the value of
MutationRecord.type
being
"attributes"
), a function called
notifyUser()
is used to tell the user the name of the attribute that changed as well as the attribute's new value (
mutation.target[mutation.attributeName]
) and its old value (
mutation.oldValue
).
当
observe()
is called, the specified options are
属性
and
attributeOldValue
, which means that changes to attribute values will be reported, and each mutation record will include the
oldValue
property specifying the attribute's previous value.
| 规范 | 状态 | 注释 |
|---|---|---|
|
DOM
The definition of 'MutationObserverInit.attributes' in that specification. |
实时标准 |
| 桌面 | 移动 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
属性
|
Chrome
26
|
Edge 12 |
Firefox
14
注意事项
|
IE 11 | Opera 15 |
Safari
7
|
WebView Android ? |
Chrome Android
26
|
Firefox Android
14
注意事项
|
Opera Android 14 |
Safari iOS
7
|
Samsung Internet Android
1.5
|
完整支持
兼容性未知
见实现注意事项。
要求使用供应商前缀或不同名称。