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PerformanceEntry

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨2017年9月⁩.

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

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");    }  }}