javascript - 监听 HTML 渲染进程事件

Question

我正在阅读一些关于渲染过程的文章:

https://developers.google.com/web/fundamentals/performance/ http://www.sitepoint.com/optimizing-critical-rendering-path/

我希望能够监听渲染过程中发生的步骤事件，能够知道浏览器何时开始(和结束)处理 HTML 文档，何时将 css 规则添加到 CSSOM树，...

实际上，我正在查找 devtools timeline 中显示的信息, 但采用正式格式。

我认为没有标准化模型，但可能某些浏览器允许监听这些事件。

Answer 1

您可以只使用 Navigation Timing API 中的只读属性, IDL接口(interface):

interface PerformanceTiming {
  readonly attribute unsigned long long navigationStart;
  readonly attribute unsigned long long unloadEventStart;
  readonly attribute unsigned long long unloadEventEnd;
  readonly attribute unsigned long long redirectStart;
  readonly attribute unsigned long long redirectEnd;
  readonly attribute unsigned long long fetchStart;
  readonly attribute unsigned long long domainLookupStart;
  readonly attribute unsigned long long domainLookupEnd;
  readonly attribute unsigned long long connectStart;
  readonly attribute unsigned long long connectEnd;
  readonly attribute unsigned long long secureConnectionStart;
  readonly attribute unsigned long long requestStart;
  readonly attribute unsigned long long responseStart;
  readonly attribute unsigned long long responseEnd;
  readonly attribute unsigned long long domLoading;
  readonly attribute unsigned long long domInteractive;
  readonly attribute unsigned long long domContentLoadedEventStart;
  readonly attribute unsigned long long domContentLoadedEventEnd;
  readonly attribute unsigned long long domComplete;
  readonly attribute unsigned long long loadEventStart;
  readonly attribute unsigned long long loadEventEnd;
};

满了description from MDN .

但是你不能监听 performance.timing 对象的变化。