好吧，现在是2017年，所以你现在有网络信息API(尽管目前跨浏览器的支持有限)来获得某种估计的下行速度信息:

navigator.connection.downlink

这是以Mbits / sec为单位的有效带宽估计。浏览器根据最近观察到的应用程序层在最近活动连接上的吞吐量进行估计。不用说，这种方法的最大优点是，您不需要下载任何内容，只是为了带宽/速度计算。

你可以看看这个和其他一些相关的属性

由于它的支持有限，并且跨浏览器的实现不同(截至2017年11月)，强烈建议详细阅读这篇文章

//JUST AN EXAMPLE, PLEASE USE YOUR OWN PICTURE! var imageAddr = "https://i.ibb.co/sPbbkkZ/pexels-lisa-1540258.jpg"; var downloadSize = 10500000; //bytes function ShowProgressMessage(msg) { if (console) { if (typeof msg == "string") { console.log(msg); } else { for (var i = 0; i < msg.length; i++) { console.log(msg[i]); } } } var oProgress = document.getElementById("progress"); if (oProgress) { var actualHTML = (typeof msg == "string") ? msg : msg.join("<br />"); oProgress.innerHTML = actualHTML; } } function InitiateSpeedDetection() { ShowProgressMessage("Loading the image, please wait..."); window.setTimeout(MeasureConnectionSpeed, 1); }; if (window.addEventListener) { window.addEventListener('load', InitiateSpeedDetection, false); } else if (window.attachEvent) { window.attachEvent('onload', InitiateSpeedDetection); } function MeasureConnectionSpeed() { var startTime, endTime; var download = new Image(); download.onload = function () { endTime = (new Date()).getTime(); showResults(); } download.onerror = function (err, msg) { ShowProgressMessage("Invalid image, or error downloading"); } startTime = (new Date()).getTime(); var cacheBuster = "?nnn=" + startTime; download.src = imageAddr + cacheBuster; function showResults() { var duration = (endTime - startTime) / 1000; var bitsLoaded = downloadSize * 8; var speedBps = (bitsLoaded / duration).toFixed(2); var speedKbps = (speedBps / 1024).toFixed(2); var speedMbps = (speedKbps / 1024).toFixed(2); ShowProgressMessage([ "Your connection speed is:", speedBps + " bps", speedKbps + " kbps", speedMbps + " Mbps" ]); } } <h1 id="progress">JavaScript is turned off, or your browser is realllllly slow</h1>

As I outline in this other answer here on StackOverflow, you can do this by timing the download of files of various sizes (start small, ramp up if the connection seems to allow it), ensuring through cache headers and such that the file is really being read from the remote server and not being retrieved from cache. This doesn't necessarily require that you have a server of your own (the files could be coming from S3 or similar), but you will need somewhere to get the files from in order to test connection speed.

也就是说，时间点带宽测试是出了名的不可靠，因为它们会受到其他窗口中正在下载的其他项目、服务器的速度、路由中的链接等的影响。但是你可以用这种方法得到一个大致的概念。

好吧，现在是2017年，所以你现在有网络信息API(尽管目前跨浏览器的支持有限)来获得某种估计的下行速度信息:

navigator.connection.downlink

这是以Mbits / sec为单位的有效带宽估计。浏览器根据最近观察到的应用程序层在最近活动连接上的吞吐量进行估计。不用说，这种方法的最大优点是，您不需要下载任何内容，只是为了带宽/速度计算。

你可以看看这个和其他一些相关的属性

由于它的支持有限，并且跨浏览器的实现不同(截至2017年11月)，强烈建议详细阅读这篇文章

图像技巧很酷，但在我的测试中，它是在我想完成的一些ajax调用之前加载的。

2017年合适的解决方案是使用工人(http://caniuse.com/#feat=webworkers)。

工人看起来像这样:

/**
 * This function performs a synchronous request
 * and returns an object contain informations about the download
 * time and size
 */
function measure(filename) {
  var xhr = new XMLHttpRequest();
  var measure = {};
  xhr.open("GET", filename + '?' + (new Date()).getTime(), false);
  measure.start = (new Date()).getTime();
  xhr.send(null);
  measure.end = (new Date()).getTime();
  measure.len = parseInt(xhr.getResponseHeader('Content-Length') || 0);
  measure.delta = measure.end - measure.start;
  return measure;
}

/**
 * Requires that we pass a base url to the worker
 * The worker will measure the download time needed to get
 * a ~0KB and a 100KB.
 * It will return a string that serializes this informations as
 * pipe separated values
 */
onmessage = function(e) {
  measure0 = measure(e.data.base_url + '/test/0.bz2');
  measure100 = measure(e.data.base_url + '/test/100K.bz2');
  postMessage(
    measure0.delta + '|' +
    measure0.len + '|' +
    measure100.delta + '|' +
    measure100.len
  );
};

调用Worker的js文件:

var base_url = PORTAL_URL + '/++plone++experimental.bwtools';
if (typeof(Worker) === 'undefined') {
  return; // unsupported
}
w = new Worker(base_url + "/scripts/worker.js");
w.postMessage({
  base_url: base_url
});
w.onmessage = function(event) {
  if (event.data) {
    set_cookie(event.data);
  }
};

摘自我编写的Plone包的代码:

https://github.com/collective/experimental.bwtools/blob/master/src/experimental/bwtools/browser/static/scripts/

改进了John Smith的答案，一个漂亮而干净的解决方案，返回一个Promise，因此可以与async/await一起使用。返回以Mbps为单位的值。

const imageAddr = 'https://upload.wikimedia.org/wikipedia/commons/a/a6/Brandenburger_Tor_abends.jpg';
const downloadSize = 2707459; // this must match with the image above

let startTime, endTime;
async function measureConnectionSpeed() {
  startTime = (new Date()).getTime();
  const cacheBuster = '?nnn=' + startTime;

  const download = new Image();
  download.src = imageAddr + cacheBuster;
  // this returns when the image is finished downloading
  await download.decode();
  endTime = (new Date()).getTime();
  const duration = (endTime - startTime) / 1000;
  const bitsLoaded = downloadSize * 8;
  const speedBps = (bitsLoaded / duration).toFixed(2);
  const speedKbps = (speedBps / 1024).toFixed(2);
  const speedMbps = (speedKbps / 1024).toFixed(2);
  return Math.round(Number(speedMbps));
}