Chrome 64 即将弃用 chrome.loadTimes() API

Philip Walton
Philip Walton
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chrome.loadTimes() 是一种非标准 API，会向开发者提供加载指标和网络信息，以帮助他们更好地了解其网站在实际中的性能。

由于此 API 于 2009 年实施，因此它报告的所有实用信息都可以在标准化 API 中找到，例如：

这些标准化 API 正由多个浏览器供应商实施。因此，Chrome 64 中废弃了 chrome.loadTimes()。

已废弃的 API

chrome.loadTimes() 函数会返回单个对象，其中包含其所有加载信息和网络信息。例如，以下对象是在 www.google.com 上调用 chrome.loadTimes() 的结果：

{
  "requestTime": 1513186741.847,
  "startLoadTime": 1513186741.847,
  "commitLoadTime": 1513186742.637,
  "finishDocumentLoadTime": 1513186742.842,
  "finishLoadTime": 1513186743.582,
  "firstPaintTime": 1513186742.829,
  "firstPaintAfterLoadTime": 0,
  "navigationType": "Reload",
  "wasFetchedViaSpdy": true,
  "wasNpnNegotiated": true,
  "npnNegotiatedProtocol": "h2",
  "wasAlternateProtocolAvailable": false,
  "connectionInfo": "h2"
}

标准化换货

现在，您可以使用标准化 API 找到上述每个值。下表将每个值与其标准化 API 进行匹配；下文还显示了如何使用现代等效项获取旧 API 中的每个值。

chrome.loadTimes() 功能 标准化 API 替换
requestTime 导航计时 2
startLoadTime 导航计时 2
commitLoadTime 导航计时 2
finishDocumentLoadTime 导航计时 2
finishLoadTime 导航计时 2
firstPaintTime 绘制时间
firstPaintAfterLoadTime 不适用
navigationType 导航计时 2
wasFetchedViaSpdy 导航计时 2
wasNpnNegotiated 导航计时 2
npnNegotiatedProtocol 导航计时 2
wasAlternateProtocolAvailable 不适用
connectionInfo 导航计时 2

以下代码示例返回的值与 chrome.loadTimes() 返回的值相同。不过，对于新代码，不推荐使用这些代码示例。原因是 chrome.loadTimes() 提供的时间值以纪元时间（以秒为单位）为单位，而新的性能 API 通常以毫秒为单位来报告与网页的时间原点相关的值，这往往对性能分析更有用。

其中几个示例也支持 Performance Timeline 2 API（例如 performance.getEntriesByType()），但针对旧版 Navigation Timing 1 API 提供了回退机制，因为它具有更广泛的浏览器支持。今后，建议使用 Performance Timeline API，并且通常以更高的精确度进行报告。

requestTime

function requestTime() {
  // If the browser supports the Navigation Timing 2 and HR Time APIs, use
  // them, otherwise fall back to the Navigation Timing 1 API.
  if (window.PerformanceNavigationTiming && performance.timeOrigin) {
    const ntEntry = performance.getEntriesByType('navigation')[0];
    return (ntEntry.startTime + performance.timeOrigin) / 1000;
  } else {
    return performance.timing.navigationStart / 1000;
  }
}

startLoadTime

function startLoadTime() {
  // If the browser supports the Navigation Timing 2 and HR Time APIs, use
  // them, otherwise fall back to the Navigation Timing 1 API.
  if (window.PerformanceNavigationTiming && performance.timeOrigin) {
    const ntEntry = performance.getEntriesByType('navigation')[0];
    return (ntEntry.startTime + performance.timeOrigin) / 1000;
  } else {
    return performance.timing.navigationStart / 1000;
  }
}

commitLoadTime

function commitLoadTime() {
  // If the browser supports the Navigation Timing 2 and HR Time APIs, use
  // them, otherwise fall back to the Navigation Timing 1 API.
  if (window.PerformanceNavigationTiming && performance.timeOrigin) {
    const ntEntry = performance.getEntriesByType('navigation')[0];
    return (ntEntry.responseStart + performance.timeOrigin) / 1000;
  } else {
    return performance.timing.responseStart / 1000;
  }
}

finishDocumentLoadTime

function finishDocumentLoadTime() {
  // If the browser supports the Navigation Timing 2 and HR Time APIs, use
  // them, otherwise fall back to the Navigation Timing 1 API.
  if (window.PerformanceNavigationTiming && performance.timeOrigin) {
    const ntEntry = performance.getEntriesByType('navigation')[0];
    return (ntEntry.domContentLoadedEventEnd + performance.timeOrigin) / 1000;
  } else {
    return performance.timing.domContentLoadedEventEnd / 1000;
  }
}

finishLoadTime

function finishLoadTime() {
  // If the browser supports the Navigation Timing 2 and HR Time APIs, use
  // them, otherwise fall back to the Navigation Timing 1 API.
  if (window.PerformanceNavigationTiming && performance.timeOrigin) {
    const ntEntry = performance.getEntriesByType('navigation')[0];
    return (ntEntry.loadEventEnd + performance.timeOrigin) / 1000;
  } else {
    return performance.timing.loadEventEnd / 1000;
  }
}

firstPaintTime

function firstPaintTime() {
  if (window.PerformancePaintTiming) {
    const fpEntry = performance.getEntriesByType('paint')[0];
    return (fpEntry.startTime + performance.timeOrigin) / 1000;
  }
}

firstPaintAfterLoadTime

function firstPaintTimeAfterLoad() {
  // This was never actually implemented and always returns 0.
  return 0;
}

function navigationType() {
  if (window.PerformanceNavigationTiming) {
    const ntEntry = performance.getEntriesByType('navigation')[0];
    return ntEntry.type;
  }
}

wasFetchedViaSpdy

function wasFetchedViaSpdy() {
  // SPDY is deprecated in favor of HTTP/2, but this implementation returns
  // true for HTTP/2 or HTTP2+QUIC/39 as well.
  if (window.PerformanceNavigationTiming) {
    const ntEntry = performance.getEntriesByType('navigation')[0];
    return ['h2', 'hq'].includes(ntEntry.nextHopProtocol);
  }
}

wasNpnNegotiated

function wasNpnNegotiated() {
  // NPN is deprecated in favor of ALPN, but this implementation returns true
  // for HTTP/2 or HTTP2+QUIC/39 requests negotiated via ALPN.
  if (window.PerformanceNavigationTiming) {
    const ntEntry = performance.getEntriesByType('navigation')[0];
    return ['h2', 'hq'].includes(ntEntry.nextHopProtocol);
  }
}

npnNegotiatedProtocol

function npnNegotiatedProtocol() {
  // NPN is deprecated in favor of ALPN, but this implementation returns the
  // HTTP/2 or HTTP2+QUIC/39 requests negotiated via ALPN.
  if (window.PerformanceNavigationTiming) {
    const ntEntry = performance.getEntriesByType('navigation')[0];
    return ['h2', 'hq'].includes(ntEntry.nextHopProtocol) ?
        ntEntry.nextHopProtocol : 'unknown';
  }
}

wasAlternateProtocolAvailable

function wasAlternateProtocolAvailable() {
  // The Alternate-Protocol header is deprecated in favor of Alt-Svc
  // (https://www.mnot.net/blog/2016/03/09/alt-svc), so technically this
  // should always return false.
  return false;
}

connectionInfo

function connectionInfo() {
  if (window.PerformanceNavigationTiming) {
    const ntEntry = performance.getEntriesByType('navigation')[0];
    return ntEntry.nextHopProtocol;
  }
}

移除计划

chrome.loadTimes() API 将在 Chrome 64 中弃用，并计划于 2018 年底移除。开发者应尽快迁移其代码，以免数据丢失。

打算弃用 | Chromestatus Tracker | Chromium 错误