<!doctype html>
<html>
<head>
<meta http-equiv=Content-Type content="text/html;charset=utf-8">
<title>js实现的网速测试方法</title>
</head>
<body>
<script>
function testBW(fn) {
var startTime, endTime, fileSize;
var xhr = new XMLHttpRequest();
xhr.timeout=30000;
xhr.onerror=function (){
console.log(‘onerror‘);
}
xhr.onreadystatechange =function(){
console.log(JSON.stringify(xhr));
if(xhr.readyState === 2){
startTime = Date.now();
}
if (xhr.readyState === 4) {
endTime = Date.now();
console.log(xhr.readyState+‘==‘+xhr.responseText.length);
fileSize = xhr.responseText.length;
console.log(fileSize);
var speed = fileSize / ((endTime - startTime)/1000) / 1024;
fn && fn(Math.floor(speed)||0)
console.log(‘complete‘);
}
if(xhr.status === 200) {
endTime = Date.now();
console.log(xhr.readyState+‘==‘+xhr.responseText.length);
fileSize = xhr.responseText.length;
console.log(fileSize);
var speed = fileSize / ((endTime - startTime)/1000) / 1024;
fn && fn(Math.floor(speed)||0)
}
}
//http://wangsu3s.acc5.com/ping.jpg
//http://alyun3s.acc5.com/ping.jpg
//http://app-static.acc5.com/app/ping.gif
xhr.open("GET", "http://app-static.acc5.com/app/ping.gif?rnd=" + Math.random(), true);
xhr.send();
}
function callback(speed){
document.write("<div id=‘div1‘>"+speed + " KB/s</div>");
console.log(speed + " KB/s"); //215 KB/sec
}
testBW(callback);
</script>
</body>
</html>
原文：https://www.cnblogs.com/xuan52rock/p/11008679.html