/*
  - Give Credit Where Its Due -
  Please acknowledge this article and its author, at
  least in code comments, when using this code.

  Author: Justin Whitford
  Source: www.evolt.org

  Thank you.
*/

/*
  filtery(pattern, list)
  pattern: a string of zero or more characters by which to filter the list
  list: reference to a form object of type, select

  Example:
  <form name="yourForm">
    <input type="text" name="yourTextField" onchange="filtery(this.value,this.form.yourSelect)">
    <select name="yourSelect">
      <option></option>
      <option value="Australia">Australia</option>
       .......
*/
function filtery(pattern, list){
  /*
  if the dropdown list passed in hasn't
  already been backed up, we'll do that now
  */
  if (!list.bak){
    /*
    We're going to attach an array to the select object
    where we'll keep a backup of the original dropdown list
    */
    list.bak = new Array();
    for (n=0;n<list.length;n++){
      list.bak[list.bak.length] = new Array(list[n].value, list[n].text);
    }
  }

  /*
  We're going to iterate through the backed up dropdown
  list. If an item matches, it is added to the list of
  matches. If not, then it is added to the list of non matches.
  */
  match = new Array();
  nomatch = new Array();
  for (n=0;n<list.bak.length;n++){
    if(list.bak[n][1].toLowerCase().indexOf(pattern.toLowerCase())!=-1){
      match[match.length] = new Array(list.bak[n][0], list.bak[n][1]);
    }else{
      nomatch[nomatch.length] = new Array(list.bak[n][0], list.bak[n][1]);
    }
  }

  /*
  Now we completely rewrite the dropdown list.
  First we write in the matches, then we write
  in the non matches
  */
  for (n=0;n<match.length;n++){
    list[n].value = match[n][0];
    list[n].text = match[n][1];
  }
  for (n=0;n<nomatch.length;n++){
    list[n+match.length].value = nomatch[n][0];
    list[n+match.length].text = nomatch[n][1];
  }

  /*
  Finally, we make the 1st item selected - this
  makes sure that the matching options are
  immediately apparent
  */
  list.selectedIndex=0;
}