Js detection file type and size

Function CheckFileType ()
{
Var objButton = document. getElementById ("buttonsubmit ");
Var objFileUpload = document. getElementById ('upload ');

Var objMSG = document. getElementById ('msg ');
Var FileName = new String (objFileUpload. value );
Var extension = new String (FileName. substring (FileName. lastIndexOf (".") + 1, FileName. length ));

Var image = new Image ();
Image. dynsrc = objFileUpload. value;
Var FileSize = Math. round (image. fileSize/1024*100)/100;
If (FileSize> 100)
{
ObjButton. disabled = true;
ObjMSG. innerHTML = "<div style = 'border: # CCCCCC dotted 1px; background-color: # FFFFCC; padding: 5px; margin: 10px auto; color: # FF0000; '> File too large. </div> ";
Return;
}

If (extension. toLowerCase () = "xls" | extension. toLowerCase () = "csv ")
{
ObjButton. disabled = false;
ObjMSG. innerHTML = "";
}
Else
{
ObjButton. disabled = true;
ObjMSG. innerHTML = "<div style = 'border: # CCCCCC dotted 1px; background-color: # FFFFCC; padding: 5px; margin: 10px auto; color: # FF0000; '> FileType error. </div> ";
}
}

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Function CheckFileType ()
{
Var objButton = document. getElementById ("buttonsubmit ");
Var objFileUpload = document. getElementById ('upload ');
Var FileSize = Math. round (getFileSize (objFileUpload. value)/1024*100)/100; // obtain the image file size
Var objMSG = document. getElementById ('msg ');
Var FileName = new String (objFileUpload. value );
Var extension = new String (FileName. substring (FileName. lastIndexOf (".") + 1, FileName. length ));

If (FileSize> 100)
{
ObjButton. disabled = true;
ObjMSG. innerHTML = "<div style = 'border: # CCCCCC dotted 1px; background-color: # FFFFCC; padding: 5px; margin: 10px auto; color: # FF0000; '> File too large. </div> ";
Return;
}

If (extension. toLowerCase () = "xls" | extension. toLowerCase () = "csv ")
{
ObjButton. disabled = false;
ObjMSG. innerHTML = "";
}
Else
{
ObjButton. disabled = true;
ObjMSG. innerHTML = "<div style = 'border: # CCCCCC dotted 1px; background-color: # FFFFCC; padding: 5px; margin: 10px auto; color: # FF0000; '> FileType error. </div> ";
}
}

Function getFileSize (filePath)
{
Var image = new Image ();
Image. dynsrc = filePath;

Return image. fileSize; // you can check the size of an image file.

}