function check()
{
  if (document.frm.keyword.value == "")
  {
	 	alert("You have to enter a keyword !");
		return false; 
  }
  return true;
}

function SelectAll() {
  len = document.frm.elements.length;
  var i=0;
		 
  for( i=0; i<len; i++) {
	  if (document.frm.elements[i].type=='checkbox'){
			  	 document.frm.elements[i].checked = !document.frm.elements[i].checked;
				 
	  }
  }
}

function validCheckbox(){
  len = document.frm.elements.length;
  var i=0;
  var nb_checked = 0;
		 
  for( i=0; i<len; i++) {
	  if (document.frm.elements[i].type=='checkbox'){
			  	 if(document.frm.elements[i].checked)
				 		nb_checked = nb_checked + 1;													 
	  }
  } 
  if (nb_checked == 0)
  {
   	 alert ("You have to select at least one file !");
	 return false;
  }
  return true;
}