Javascript with an ascx control

Answer 1

in yours ascx control, must have the class "myClass".

window.onload = function(){
    function getElementsByClass(containerId, class) 
    { 
      container = document.getElementById(containerId);
      var all = container.all¦¦container.getElementsByTagName('*') ;
      var arr = [] 
      for(var k=0;k<all.length;k++) 
        if(all[k].getAttribute("class").indexOf("class") != -1) 
          arr[arr.length] = all[k];
      return arr;
    }

    var arrEl = getElementsByClass("container", "myClass");
    var xOnChange = function()
    {
       //this
    }

    for (var ind = 0; ind < arEL.length; ind++)
    {
       arrEl[ind].onchange = xOnChange;
    }

}

in html or aspx:

<div id="container>
   <!-- aspx controls -->
</div>

Answer 2

Set all your drop downs with a css class of "customControlDropDown" or whatever and your textbox with a css class name of "bigTextBox" or whatever and use some jQuery.

<script type='text/javascript'>
   $(document).ready(function(){
      $("select.customControlDropDown").change(function(){ //change event for all drop downs with customControlDropDown as its css class name
         var collectiveText = "";
         $("select.customControlDropDown option:selected").each(function(i){  //get all selected options in all the drop downs with customControlDropDown as its css class name
            collectiveText = collectiveText + $(this).text(); //append the item's text to a string variable
         });

         $(".bigTextBox").val(collectiveText); //set the textbox with css class name of bigTextBox with value of the string variable from above
      });
   });
</script>

I haven't tested this, but it SHOULD work. Let us know.