PerformanceObserverEntryList.getEntries() - Web APIs 编辑

The getEntries() method of the PerformanceObserverEntryList interface returns a list of explicitly observed performance entry objects for a given filter. The list's members are determined by the set of entry types specified in the call to the observe() method. The list is available in the observer's callback function (as the first parameter in the callback).

This method is exposed to Window and Worker interfaces.

Syntax

General syntax:

entries = list.getEntries();
entries = list.getEntries(PerformanceEntryFilterOptions);

Specific usage:

entries = list.getEntries({name: "entry_name", entryType: "mark"});

Parameters

PerformanceEntryFilterOptionsOptional

Is a PerformanceEntryFilterOptions dictionary, having the following fields:

• "name", the name of a performance entry.
• "entryType", the entry type. The valid entry types are listed in the PerformanceEntry.entryType method.
• "initiatorType", the type of the initiating resource (for example an HTML element). The values are defined by the PerformanceResourceTiming.initiatorType interface.

This parameter is currently not supported on Chrome or Opera.

Return value

A list of explicitly observed PerformanceEntry objects that meets the criteria of the filter. The items will be in chronological order based on the entries' startTime. If no objects that meet the filter are found, an empty list is returned. If no argument is given, all entries are returned.

Example

function print_perf_entry(pe) {
  console.log("name: "        + pe.name      +
              "; entryType: " + pe.entryType +
              "; startTime: " + pe.startTime +
              "; duration: "  + pe.duration);
}

// Create observer for all performance event types
var observe_all = new PerformanceObserver(function(list, obs) {
  var perfEntries;

  // Print all entries
  perfEntries = list.getEntries();
  for (var i=0; i < perfEntries.length; i++) {
    print_perf_entry(perfEntries[i]);
  }

  // Print entries named "Begin" with type "mark"
  perfEntries = list.getEntriesByName("Begin", "mark");
  for (var i=0; i < perfEntries.length; i++) {
    print_perf_entry(perfEntries[i]);
  }

  // Print entries with type "mark"
  perfEntries = list.getEntriesByType("mark");
  for (var i=0; i < perfEntries.length; i++) {
    print_perf_entry(perfEntries[i]);
  }
});
// subscribe to all performance event types
observe_all.observe({entryTypes: ['frame', 'mark', 'measure', 'navigation', 'resource', 'server']});

var observe_frame = new PerformanceObserver(function(list, obs) {
  var perfEntries = list.getEntries();
  // Should only have 'frame' entries
  for (var i=0; i < perfEntries.length; i++) {
    print_perf_entry(perfEntries[i]);
  }
});
// subscribe to frame event only
observe_frame.observe({entryTypes: ['frame']});

Specifications

Browser compatibility

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