PerformanceEntry

PerformanceEntry 객체는 performance timeline 상의 단일 성능 수치를 캡슐화 합니다. performance entry는 응용프로그램의 특정 지점에서 performance mark (en-US)나 measure (en-US)를 생성함으로써 (예를 들면 mark()를 호출하는 방법으로) 직접적으로 만들어질 수 있습니다. 또는 (이미지와 같은) 리소스를 로딩하는 등의 간접적인 방법으로 생성되기도 합니다.

PerformanceEntry 인스턴스는 항상 다음 서브타입들 중 하나를 따릅니다:

• PerformanceMark (en-US)
• PerformanceMeasure (en-US)
• PerformanceFrameTiming (en-US)
• PerformanceNavigationTiming (en-US)
• PerformanceResourceTiming (en-US)
• PerformancePaintTiming (en-US)

PerformanceEntry.name (en-US) Read only

A value that further specifies the value returned by the PerformanceEntry.entryType (en-US) property. The value of both depends on the subtype. See property page for valid values.

PerformanceEntry.entryType (en-US) Read only

A DOMString representing the type of performance metric such as, for example, "mark". See property page for valid values.

PerformanceEntry.startTime (en-US) Read only

A DOMHighResTimeStamp (en-US) representing the starting time for the performance metric.

PerformanceEntry.duration (en-US) Read only

A DOMHighResTimeStamp (en-US) representing the time value of the duration of the performance event.

PerformanceEntry.toJSON() (en-US)

Returns a JSON representation of the PerformanceEntry object.

The following example checks all PerformanceEntry properties to see if the browser supports them and if so, write their values to the console.

function print_PerformanceEntries() {
  // Use getEntries() to get a list of all performance entries
  var p = performance.getEntries();
  for (var i=0; i < p.length; i++) {
    console.log("PerformanceEntry[" + i + "]");
    print_PerformanceEntry(p[i]);
  }
}
function print_PerformanceEntry(perfEntry) {
  var properties = ["name",
                    "entryType",
                    "startTime",
                    "duration"];

  for (var i=0; i < properties.length; i++) {
    // Check each property
    var supported = properties[i] in perfEntry;
    if (supported) {
      var value = perfEntry[properties[i]];
      console.log("... " + properties[i] + " = " + value);
    } else {
      console.log("... " + properties[i] + " is NOT supported");
    }
  }
}