在下面的代码中,我试图计算一个图像的下载速度,但速度是无穷大的.我究竟做错了什么？
var imageAddr = "/images/image.jpg" + "?n=" + Math.random();
var startTime,endTime;
var downloadSize = 200000;
var download = new Image();
download.onload = function () {
endTime = (new Date()).getTime();
showResults();
}
startTime = (new Date()).getTime();
download.src = imageAddr;
function showResults() {
var duration = Math.round((endTime - startTime) / 1000);
var bitsLoaded = downloadSize * 8;
var speedBps = Math.round(bitsLoaded / duration);
var speedKbps = (speedBps / 1024).toFixed(2);
var speedMbps = (speedKbps / 1024).toFixed(2);
alert("Your connection speed is: \n" +
speedBps + " bps\n" +
speedKbps + " kbps\n" +
speedMbps + " Mbps\n" );
}
解决方法
持续时间可能会超出0,并且正数除以零可以产生JavaScript中正无穷大的特殊值.
