// thanks to GOOD OLE MICROSOFT, I can provide you the following working
// example of a DROP DOWN LIST that allows you to type more than the
// FIRST LETTER of what you are looking for in a drop down.
// I hopw that you find this to be useful. I have been looking for this
// code for almost a year now. 
// Again, do not vote for me as this code is from Microsoft.
// Respectfully, Jason Buck jbuck@esubinc.com
// Happy Programming.
// The CODE WAS FOUND at the following location
// http://msdn.microsoft.com/msdnmag/issues/01/05/web/figures.asp
// Auto-select listbox
// mike pope, Visual Basic UE
// This script and the listbox on this page illustrates one 
// way to create an "auto-complete" listbox, where the

var toFind = ""; // Variable that acts as keyboard buffer
var timeoutID = "";// Process id for timer (used when stopping the timeout)
var timeoutInterval = 400;// Milliseconds. Shorten to cause keyboard buffer to be cleared faster
var timeoutCtr = 0;// Initialization of timer count down
var timeoutCtrLimit = 3 ; // Number of times to allow timer to count down
var oControl = "";// Maintains a global reference to the control that the user is working with.

function listbox_onkeypress(){
  // This function is called when the user presses a key while focus is in 
  // the listbox. It maintains the keyboard buffer.
  // Each time the user presses a key, the timer is restarted. 
  // First, stop the previous timer; this function will restart it.
  window.clearInterval(timeoutID)
  // Which control raised the event? We'll need to know which control to 
  // set the selection in.
  oControl = window.event.srcElement;
  var keycode = window.event.keyCode;
  if(keycode >= 32 ){
    // What character did the user type?
    var c = String.fromCharCode(keycode);
    c = c.toUpperCase(); 
    // Convert it to uppercase so that comparisons don't fail
    toFind += c ; // Add to the keyboard buffer
    find();// Search the listbox
    timeoutID = window.setInterval("idle()", timeoutInterval); 
    // Restart the timer
  }
}

function listbox_onblur(){
  // This function is called when the user leaves the listbox.
  window.clearInterval(timeoutID);
  resetToFind();
}

function idle(){
  // This function is called if the timeout expires. If this is the 
  // third (by default) time that the idle function has been called, 
  // it stops the timer and clears the keyboard buffer
  timeoutCtr += 1
  if(timeoutCtr > timeoutCtrLimit){
    resetToFind();
    timeoutCtr = 0;
    window.clearInterval(timeoutID);
  }
}

function resetToFind(){
  toFind = ""
}

function find(){
  // Walk through the select list looking for a match
  var allOptions = document.all.item(oControl.id);
  for (i=0; i < allOptions.length; i++){

    // Gets the next item from the listbox

    nextOptionText = allOptions(i).text.toUpperCase();

    // By default, the values in the listbox and as entered by the 

    // user are strings. This causes a string comparison to be made, 

    // which is not correct for numbers (1 < 11 < 2).

    // The following lines coerce numbers into an (internal) number 

    // format so that the subsequent comparison is done as a 

    // number (1 < 2 < 11).

    if(!isNaN(nextOptionText) && !isNaN(toFind) ){

       nextOptionText *= 1;// coerce into number

       toFind *= 1;

    }

    // Does the next item match exactly what the user typed?

    if(toFind == nextOptionText){

       // OK, we can stop at this option. Set focus here

       oControl.selectedIndex = i;

       window.event.returnValue = false;

       break;

    }

    // If the string does not match exactly, find which two entries 

    // it should be between.

    if(i < allOptions.length-1){

       // If we are not yet at the last listbox item, see if the 

       // search string comes between the current entry and the next 

       // one. If so, place the selection there.

       lookAheadOptionText = allOptions(i+1).text.toUpperCase() ;

       if((toFind > nextOptionText) && (toFind < lookAheadOptionText) ){

         oControl.selectedIndex = i+1;

         window.event.cancelBubble = true;

         window.event.returnValue = false;

         break;

       } // if

    } // if

    else{

      // If we are at the end of the entries and the search string 

      // is still higher than the entries, select the last entry

      if(toFind > nextOptionText){
        oControl.selectedIndex = allOptions.length-1 // stick it 
        // at the end
        window.event.cancelBubble = true;
        window.event.returnValue = false;
        break;
      } // if
    } // else
  } // for
} // function