PerformanceEntry

PerformanceEntry 对象代表了 performance 时间列表中的单个 metric 数据. 每一个 performance entry 都可以在应用运行过程中通过手动构建 mark (en-US) 或者 measure (en-US) (例如调用 mark() 方法) 生成. 此外, Performance entries 在资源加载的时候,也会被动生成(例如图片、script、css等资源加载)

Note: Performance 对象暴露给了 WindowWorker. 同时该对象扩展了几个其他对象的属性,包括 PerformanceMark (en-US), PerformanceMeasure (en-US), PerformanceFrameTiming, PerformanceNavigationTiming 以及 PerformanceResourceTiming.

Properties

PerformanceEntry.name 只读
DOMString 该 performance entry 的名字
PerformanceEntry.entryType 只读
DOMString 代表所上报的 performance metric 的 entryType 类型,例如 "mark". 可以通过 entryType 查阅完整的 entryType type 类型.
PerformanceEntry.startTime (en-US) 只读
 DOMHighResTimeStamp  此为 metric 上报时的时间
PerformanceEntry.duration 只读
DOMHighResTimeStamp 该事件的耗时

Methods

PerformanceEntry.toJSON()
返回 PerformanceEntry 对象的 JSON 格式数据
 

Example

以下例子检查了当前浏览器所支持的所有 PerformanceEntry 属性,每个属性的检查结果都会通过 console 打印出来

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] + " = NOT supported");
    }
  }
}

Specifications

Specification Status Comment
Performance Timeline Level 2
PerformanceEntry
Candidate Recommendation Added toJSON() serializer method.
Performance Timeline
PerformanceEntry
Recommendation Initial definition.

Browser compatibility

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