js ajax method to obtain file size_javascript skills

The example in this article describes the method of obtaining the file size through js ajax. Share it with everyone for your reference, the details are as follows:

As the name suggests, you can get the size of the uploaded file through JS and Ajax. You can make a judgment before uploading and control the uploaded file, because there are some problems with js controlling the file size (JS getting the file size). Please give it a try. That’s it. I’ve sorted out the ajax method of obtaining the file size. It’s relatively easy to use. During the debugging process, an error of c:/fakepath/ occurred. The solution is also listed below for your reference

No further nonsense, the code is as follows

JS is as follows:

<script language="Jscript">
function chksize(){
  var ticketType = "Oil";
  var file1=document.getElementById("txtfile");
  var v = file1.value;
  file1.select();
  var realpath = document.selection.createRange().text;
  var input = "<Record><Type>TicketLoanResult</Type><TicketType>" + realpath + "</TicketType></Record>";
  var objXmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
  objXmlHttp.Open("POST", "XMLHttpPost.aspx", false);
  objXmlHttp.Send(input);
  var returnXml = objXmlHttp.responseText;
  if(returnXml!=null)
  {
   returnXml=parseInt(returnXml/1024/1024);
  }
  alert(returnXml); 
  return false; 
}
</script>

Backend C# code:

public partial class XMLHttpPost : System.Web.UI.Page
{
 protected void Page_Load(object sender, EventArgs e)
 {
  try
  {
   XmlDocument xmlDocumenet = new XmlDocument();
   xmlDocumenet.Load(Request.InputStream);
   string type = xmlDocumenet.SelectSingleNode("descendant::Type").InnerText;
   string returnMessage = string.Empty;
   switch (type.Trim())
   {
    case "TicketLoanResult":
     returnMessage = GetTicketLoanResult(xmlDocumenet);
     break;
    default:
     break;
   }
   Response.ContentType = "text/xml";
   Response.Write(returnMessage);
  }
  catch (Exception exceptional)
  {
   //如果有錯誤則返回錯誤信息（Xml格式）
   string errorMessage = "<Error>" + exceptional.Message + "</Error>";
   Response.ContentType = "text/xml";
   Response.Write(errorMessage);
  }
  finally
  {
   Response.End();
  }
 }
 private string GetTicketLoanResult(XmlDocument input)
 {
  XmlNode item = input.SelectSingleNode("descendant::TicketType");
  string ticketType = item.InnerText.Trim();
  FileStream stream = new FileStream(ticketType,FileMode.Open);
  return stream.Length.ToString();
 }
}

Click here for the complete example codeDownload from this site.

I hope this article will be helpful to everyone in JavaScript programming.