js上传文件js 上传单个文件(任意大小)

js上传文件:js 上传单个文件(任意大小) 
疯狂代码 http://www.CrazyCoder.cn/ :http:/www.CrazyCoder.cn/Javascript/Article8329.html 

varxml_http,ado_stream; 
varSendBlockCount,SendCount; 
varlastSendTime,maxFileLimit; 
varbreaked=false; 
var_filename; 
varblockSize=1024*128; 
varisUploaded=false; 

maxFileLimit=1024*1024*50;//上传文件的大小 


///处理文件开始上传 
functionBeginSend() 
{ 
try 
{ 
if(document.getElementById(\"UpFileControl\")&&document.getElementById(\"UpFileControl\").value
.length>0) 
{ 
document.getElementById(\"speed\").innerHTML=\"0KB/Sec\";//进度条 
document.getElementById(\"perent\").innerHTML=\"0%\"; 
document.getElementById(\"perentBar\").style.width=\"0%\"; 
document.getElementById(\"bar\").style.display=\"block\"; 
//document.getElementById(\"control\").style.display=\"block\"; 
document.getElementById(\"divImportData\").style.display=\"block\"; 
_filename=document.getElementById(\"UpFileControl\").value; 
document.getElementById(\"filename\").innerHTML=\"正在上传文件