测试网速可以使用XMLHttpRequest对象的onprogress事件实现

测网速原理.js

function speedtest() {
  var xmlhttp = new XMLHttpRequest(),
    method = "GET",
    url = "http://109.123.87.183/speedtest.256mb";
  const start = Date.now();
  xmlhttp.open(method, url, true);
  xmlhttp.onprogress = function (e) {
    const dnow = Date.now();
    const miao = (dnow - start) / 1000;
    const mb = 1024 * 1024;
    console.log(
      miao + "s",
      "下载量：",
      e.loaded / mb + "MB",
      "总量：",
      e.total / mb + "MB",
      "网速：",
      e.loaded / miao / mb + "MB/s"
    );
  };
  xmlhttp.send();
}