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 或者 measure (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, PerformanceMeasure, 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 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

BCD tables only load in the browser