PerformanceObserverEntryList.getEntriesByType()

The getEntriesByType() method of the PerformanceObserverEntryList returns a list of explicitly observed performance entry objects for a given performance entry type. 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).

Syntax

getEntriesByType(type)

Parameters

type

The type of entry to retrieve such as "mark". The valid entry types are listed in PerformanceEntry.entryType.

Return value

A list of explicitly observed PerformanceEntry objects that have the specified type. The items will be in chronological order based on the entries' startTime. If no objects have the specified type, or no argument is provided, an empty list is returned.

Examples

Working with getEntries, getEntriesByName and getEntriesByType

The following example shows the difference between the getEntries(), getEntriesByName(), and getEntriesByType() methods.

const observer = new PerformanceObserver((list, obs) => {
  // Log all entries
  let perfEntries = list.getEntries();
  perfEntries.forEach((entry) => {
    console.log(`${entry.name}'s duration: ${entry.duration}`)
  });

  // Log entries named "debugging" with type "measure"
  perfEntries = list.getEntriesByName("debugging", "measure");
  perfEntries.forEach((entry) => {
    console.log(`${entry.name}'s duration: ${entry.duration}`)
  });

  // Log entries with type "mark"
  perfEntries = list.getEntriesByType("mark");
  perfEntries.forEach((entry) => {
    console.log(`${entry.name}'s startTime: ${entry.startTime}`)
  });
});

// Subscribe to various performance event types
observer.observe({
  entryTypes: ['mark', 'measure', 'navigation', 'resource']
});

Specifications

Specification
Performance Timeline
# dom-performanceobserverentrylist-getentriesbytype

Browser compatibility

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