observe()
方法在
PerformanceObserver
interface is used to specify the set of performance entry types to observe.
The performance entry types are specified as an array of
DOMString
objects, each naming one entry type; the type names are documented in
Performance entry type names
in
PerformanceEntry.entryType
.
When a matching performance entry is recorded, the performance observer's callback function—set when creating the
PerformanceObserver
—is invoked.
observer.observe(options);
选项
PerformanceObserverInit
dictionary with the following possible members:
entryTypes
: An array of
DOMString
objects, each specifying one performance entry type to observe. May not be used together with the "
type
" or "
buffered
" options.
type
: A single
DOMString
specifying exactly one performance entry type to observe. May not be used together with the
entryTypes
选项。
buffered
: A
布尔
flag to indicate whether buffered entries should be queued into the observer's buffer. Must be used only with the "
type
" option.
见
PerformanceEntry.entryType
for a list of valid performance entry type names. Unrecognized types are ignored, though the browser may output a warning message to the console to help developers debug their code. If no valid types are found,
observe()
不起作用。
This example creates and configures two
PerformanceObservers
; one watches for
"mark"
and
"frame"
events, and the other watches for
"measure"
事件。
var observer = new PerformanceObserver(function(list, obj) {
var entries = list.getEntries();
for (var i=0; i < entries.length; i++) {
// Process "mark" and "frame" events
}
});
observer.observe({entryTypes: ["mark", "frame"]});
function perf_observer(list, observer) {
// Process the "measure" event
}
var observer2 = new PerformanceObserver(perf_observer);
observer2.observe({entryTypes: ["measure"]});
| 规范 | 状态 | 注释 |
|---|---|---|
|
Performance Timeline Level 2
The definition of 'observe()' in that specification. |
候选推荐 |
Initial definition of
observe()
方法。
|
| 桌面 | 移动 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
observe
|
Chrome 52 | Edge ≤79 | Firefox 57 | IE 不支持 No | Opera 39 | Safari 11 | WebView Android 52 | Chrome Android 52 | Firefox Android 57 | Opera Android 41 | Safari iOS 11 | Samsung Internet Android 6.0 |
完整支持
不支持
PerformanceObserver
disconnect()
observe()
takeRecords()