• Elastic Multiple Select List:
    • As the user moves over the select list it expands to accommodate the longest option value text
    • All the "normal" multiple select list functionality is maintained
  • Filter:
    • A text field filter is added to the select list but is hidden until the select list gets focus
    • As the user types, a list of matching options are shown
    • The results can be clicked to be added or removed from the original select list (which is hidden whilst the filtered list is shown)
    • Css styling clearly shows which items have already been selected
    • Multiple items can be selected from filtered list by holding down the "shift" key.
    • A "close" button hides and resets the filter so that the user can return to using the select list in it's normal manner or move on to the next field.
    • Each time the filter is activated (mouseover on the select list) the filter list is regenerated so as to be able to maintain all the currently selected options.
    • The minimum number of characters to be typed before the filter is activated can be defined as an option
    • Being a class, it can be defined for any number of multiple select lists on the same page.
  • More on this:



var mSelect = new multipleSelectFilter(element,{[options]});

Example (gets all multiple select lists on page):
window.addEvent('domready', function() {
		new multipleSelectFilter(el,{
			'initialTxt':'search options...',


  • initLength : (numeric - default 100) Define width of select list on before expansion (and on mouseout)
  • charWidth : (numeric - default 8) Define multiplier for expansion, this will vary according to the font-family and size
  • initialTxt : (string) Text to show in filter box before user starts typing
  • minChars : (numeric - default 0) Minimum number of characters the user must type before the filter is applied
  • iconClose : (img tag) Complete img tag for close button

The Code:

var multipleSelectFilter = new Class({
  Implements: [Options],
  options: {
    initialTxt:'type here...',
  initialize: function(element,options){
    this.selectBox = $(element);
    this.selectOptions = this.selectBox.getElements('option');
    //  create array of original options
    //  find longest item and make array of options for checking later
    var optionLength = 0;
       this.selectOptions.each(function(option) {
      if(lng>optionLength) optionLength=lng;
    //  make select box expandable
        'mouseover'  :function(){ this.expand(this.selectBox,this.stretchWidth);}.bind(this),
        'mouseout':  function(){ this.expand(this.selectBox,this.options.initLength);}.bind(this)
    //  add filter
    //  wrap select list in relative layer to flow "over" items near it rather than pushing them away
    //  NOTE - do this after we have added the filter

  addWrapper: function(){
    //  wrap select list in relative layer to flow "over" items near it rather than pushing them away
    //  this also prevents any "jumping" when the filter is activted
    var wrapper = new Element('div', {
        'styles': {
            'position': 'relative',
    el.tween('width', ''+newWidth+'px');
  //  clone the original select box with all it's selected options etc
    var arr=[];
    this.selectOptions.each(function(option, index){
    return arr;
  //  add filter box
    var initialTxt    = this.options.initialTxt;
    var initLength    = this.options.initLength;
    var optionsArray  = this.optionsArray;
    var selectBox    = this.selectBox;
    var selectOptions  = this.selectOptions;
    var selectBoxName  = this.selectBox.get('name');
    var maxLength    = 0;
    var charWidth    = this.options.charWidth;
    var stretchWidth  = this.stretchWidth;
    var wrapperWidth  = initLength.toInt()+20;
    var minChars    = this.options.minChars;
    //  get select box height for filter list
    var selectBoxHeight=this.selectBox.getSize().y;
    //  filter wrapper to hold list and text box
    var filterWrapper = new Element('div',{
      'class'  : 'filterWrapper',
    //  create ul to hold items
    var filterList= new Element('ul',{
    //  add text box
     var filterTextbox = new Element('input',{
         events: {
          if(this.value==''+initialTxt+'')  this.value="";
          //  get options to create li list for filter
          var  counter=0;
          var listItems="";
            //  define select option value and text value
            //optValue=option.get('value');  //  NOT USED
            optText  =option.get('text');
            //  define length of longest item
            if(optLength>maxLength) maxLength=optLength;
            //  check if item is selected
            if(option.get('selected'))   selected='class="checked"';
            else             selected="";
            //  add option to list if value isn't empty
            listItems += '
  • '+optText+'
  • '; // increase index counter counter++; }); // define stretch width var stretchWidth=maxLength*charWidth; // check that stretch width is not less than initial length if(stretchWidth<=initLength) var stretchWidth=initLength; // add items to ul filterList.set('html',listItems); // add events for li items filterWrapper.getElements('li').addEvents({ 'mouseover':function(event){ if(event.shift){ optId=this.id.replace('opt_'+selectBoxName+'_',''); if(this.hasClass('checked')){ // remove from original select box selectOptions[optId].setProperty('selected', ''); // remove class this.removeClass('checked'); }else{ // mark as selected in original select box selectOptions[optId].setProperty('selected', 'selected'); // add class to show as selected this.addClass('checked'); } }else{ bgColor=this.getStyle('backgroundColor'); this.highlight('#FFCC00',bgColor); } }, 'click':function(){ optId=this.id.replace('opt_'+selectBoxName+'_',''); if(this.hasClass('checked')){ // remove from original select box selectOptions[optId].setProperty('selected', ''); // remove class this.removeClass('checked'); }else{ // add class to show as selected this.addClass('checked'); // mark as selected in original select box selectOptions[optId].setProperty('selected', 'selected'); } } }).setStyle('cursor','pointer'); }, 'blur':function(){ // reset deafault text if(this.value=='') this.value=initialTxt; }, 'keyup':function(){ searchStr=this.value.toLowerCase(); if(searchStr.length>minChars){ // show list once we have at least X chars (option - default 0) // hide select box for IE selectBox.set('opacity',0); // show filter select list and expand to widest item filterList.reveal().tween('width', ''+stretchWidth+'px'); }else{ //filterList.tween('width', ''+initLength+'px').dissolve(); //selectBox.show(); } // loop through options array and remove items that aren't in it //var results=0; optionsArray.each(function(item, index){ if(!item.contains(searchStr)){ // hide item from list if($('opt_'+selectBoxName+'_'+index+''))$('opt_'+selectBoxName+'_'+index+'').hide(); }else{ // show option (incase it has been hidden by previous typing) if($('opt_'+selectBoxName+'_'+index+''))$('opt_'+selectBoxName+'_'+index+'').show(); //results++; } }); } } }).inject(filterWrapper,'top'); // reset button to hide filter list var btReset = new Element('div',{ 'class':'refresh', 'title':'Close Filter', 'html':this.options.iconClose, 'events':{ 'click':function(){ // hide the temp list - do it quickly to avoid errors ;) filterList.hide(); filterWrapper.hide(); selectBox.set('opacity',1); filterTextbox.value=initialTxt; } } }).inject(filterTextbox,'after'); var clearLayer = new Element('div',{ styles:{ border:'1px dashed red', clear:'both', height:'10px' } }).inject(filterWrapper,'after'); // hide filter box filterWrapper.inject(this.selectBox,'before').hide(); selectBox.addEvents({ mouseover:function(){ filterWrapper.reveal(); } }); } });