PerformanceEntry

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2015.

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 Window 和 Worker. 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

js
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
Performance Timeline
# dom-performanceentry

Browser compatibility

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