运行效果截图如下：
具体代码如下：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title> New Document </title> <meta http-equiv="Content-Type" content="text/html; charset=gbk"/> <meta content="EditPlus"> <meta content="xinmingyang"> <meta content=""> <meta content=""> </head> <body> <SCRIPT language=JavaScript> var st = new Date(); </SCRIPT> <IMG alt="测试图片" src="https://www.jb51.net/images/logo.gif"> <div></div> <script> var arr=["网速低于50KB","网速在50-100KB之间","网速在100-200KB之间","网速在200-300KB之间","视频通讯"]; function showspeed() { var filesize =35.4; //measured in KB var et = new Date(); var speed = Math.round(filesize*1000)/(et - st); document.title=speed; var scope=(speed>0 && speed<=50)?0:(speed>50 && speed<=100)?1:(speed>=100 && speed<200)?2:(speed>=200 && speed<300)?3:4; alert(scope) document.getElementById("showtxt").innerHTML = ("您的下载速度为：" + arr[scope] + " (K/秒)") } </script> </body> </html>