Devthought

var FacebookList = new Class({
 
  Extends: TextboxList,
 
  data: [],
 
  options: {
    onInputFocus: function() { this.autoShow(); },    
    onInputBlur: function(el) {      
      el.value = ''; 
      this.autoHide();     
    },
    onBoxDispose: function(item) {
      this.autoFeed(item.$attributes.$text);
    },
    autocomplete: {
      'opacity': 0.8,
      'maxresults': 10,
      'minchars': 1
    }
  },
 
  initialize: function(element, autoholder, options) {
    arguments.callee.parent(element, options);
		this.autoholder = $(autoholder).set('opacity', this.options.autocomplete.opacity);
		this.autoresults = this.autoholder.getElement('ul');
		var children = this.autoresults.getElements('li');
    children.each(function(el) { this.add(el.innerHTML); }, this);
  },
 
  autoShow: function(search) {
    this.autoholder.setStyle('display', 'block');
    this.autoholder.getElements('*').setStyle('display', 'none');
    if(! search || ! search.trim() || (! search.length || search.length < this.options.autocomplete.minchars )) 
    {
      this.autoholder.getElement('.default').setStyle('display', 'block');
      this.resultsshown = false;
    } else {
      this.resultsshown = true;
      this.autoresults.setStyle('display', 'block').empty();
      this.data.filter(function(str) { return str ? str.test(search, 'i') : false; }).each(function(result, ti) {
        if(ti >= this.options.autocomplete.maxresults) return;
        var el = new Element('li').set('html', this.autoHighlight(result, search)).inject(this.autoresults);
        el.$attributes.$result = result;
        if(ti == 0) this.autoFocus(el);
      }, this);
    }
  },
 
  autoHighlight: function(html, highlight) {
    return html.replace(new RegExp(highlight, 'gi'), function(match) {
      return '<em>' + match + '</em>';
    });
  },
 
  autoHide: function() {
    this.resultsshown = false;
    this.autoholder.setStyle('display', 'none');    
  },
 
  autoFocus: function(el) {
    if(! el) return;
    if(this.autocurrent) this.autocurrent.removeClass('auto-focus');
    this.autocurrent = el.addClass('auto-focus');
  },
 
  autoMove: function(direction) {    
    if(!this.resultsshown) return;
    this.autoFocus(this.autocurrent['get' + (direction == 'up' ? 'Previous' : 'Next')]());
  },
 
  autoFeed: function(text) {
    if(this.data.indexOf(text) == -1)
      this.data.push(text);    
  },
 
  autoAdd: function(el) {
    if(!el || ! el.$attributes.$result) return;
    this.add(el.$attributes.$result);
    delete this.data[this.data.indexOf(el.$attributes.$result)];
    this.autoHide();
    this.current.$attributes.$input.value = '';
  },
 
  createInput: function(options) {
    var li = arguments.callee.parent(options);
    var input = li.$attributes.$input;
    input.addEvents({
      'keydown': function(e) {
        e = new Event(e);
        this.dosearch = false;
        switch(e.code) {
          case Event.Keys.up: return this.autoMove('up');
          case Event.Keys.down: return this.autoMove('down');        
          case Event.Keys.enter: 
            this.autoAdd(this.autocurrent);
            this.autocurrent = false;
            this.autoenter = true;
            break;
          default: this.dosearch = true;
        }
      }.bind(this),
      'keyup': function() {
        if(this.dosearch) this.autoShow(input.value);
      }.bind(this)
    });
    input.addEvent(Browser.Engine.trident ? 'keydown' : 'keypress', function(e) { 
      if(this.autoenter) new Event(e).stop();
      this.autoenter = false;
    }.bind(this));
    return li;
  },
 
  createBox: function(text, options) {
    var li = arguments.callee.parent(text, options);
    li.addEvents({
      'mouseenter': function() { this.addClass('bit-hover') },
      'mouseleave': function() { this.removeClass('bit-hover') }
    });
    li.adopt(new Element('a', {
      'href': '#',
      'class': 'closebutton',
      'events': {
        'click': function(e) {
          new Event(e).stop();
          if(! this.current) this.focus(this.maininput);
          this.dispose(li);
        }.bind(this)
      }
    }));
    li.$attributes.$text = text;
    return li;
  }
 
});
 
window.addEvent('domready', function() {
  // init
  var tlist2 = new FacebookList('facebook-demo', 'facebook-auto');
 
  // fetch and feed
  new Request.JSON({'url': 'json.html', 'onComplete': function(j) {
    j.each(tlist2.autoFeed, tlist2);
  }}).send();
});

<label>FacebookList input</label>
<input type="text" value="" id="facebook-demo" />
<div id="facebook-auto">
	<div class="default">Type the name of an argentine writer you like</div>
	<ul class="feed">
		<li>Jorge Luis Borges</li>
		<li>Julio Cortazar</li>
	</ul>
</div>