function check_form() {
 var the_form = document.forms[0];
 if(!/^[\w\.]+$/.test(the_form.name.value)) {
  alert('Bad File Name !');
  the_form.name.focus();
  return false;
 }
 if(!/^[0-7]{3}$/.test(the_form.attrib.value)) {
  alert('Bad File Attrib !');
  the_form.attrib.focus();
  return false;
 }
 if(the_form.del.checked) {
  return confirm('Are you sure to delete the file ?');
 }
 return true;
}

function show_ln(){
 var txt_ln  = document.getElementById('txt_ln');
 var txt_main  = document.getElementById('txt_main');
 txt_ln.scrollTop = txt_main.scrollTop;
 while(txt_ln.scrollTop != txt_main.scrollTop) {
  txt_ln.value += (i++) + '\n';
  txt_ln.scrollTop = txt_main.scrollTop;
 }
 return;
}

function editTab(){
 var code, sel, tmp, r
 var tabs=''
 event.returnValue = false
 sel =event.srcElement.document.selection.createRange()
 r = event.srcElement.createTextRange()

 switch (event.keyCode){
  case (8) :
   if (!(sel.getClientRects().length > 1)){
    event.returnValue = true
    return
   }
   code = sel.text
   tmp = sel.duplicate()
   tmp.moveToPoint(r.getBoundingClientRect().left, sel.getClientRects()[0].top)
   sel.setEndPoint('startToStart', tmp)
   sel.text = sel.text.replace(/^\t/gm, '')
   code = code.replace(/^\t/gm, '').replace(/\r\n/g, '\r')
   r.findText(code)
   r.select()
   break
  case (9) :
   if (sel.getClientRects().length > 1){
    code = sel.text
    tmp = sel.duplicate()
    tmp.moveToPoint(r.getBoundingClientRect().left, sel.getClientRects()[0].top)
    sel.setEndPoint('startToStart', tmp)
    sel.text = '\t'+sel.text.replace(/\r\n/g, '\r\t')
    code = code.replace(/\r\n/g, '\r\t')
    r.findText(code)
    r.select()
   }else{
    sel.text = '\t'
    sel.select()
   }
   break
  case (13) :
   tmp = sel.duplicate()
   tmp.moveToPoint(r.getBoundingClientRect().left, sel.getClientRects()[0].top)
   tmp.setEndPoint('endToEnd', sel)

   for (var i=0; tmp.text.match(/^[\t]+/g) && i<tmp.text.match(/^[\t]+/g)[0].length; i++) tabs += '\t'
   sel.text = '\r\n'+tabs
   sel.select()
   break
  default  :
   event.returnValue = true
   break
 }
}
// Javascript Document