<script language="JavaScript" type="text/javascript">

// first combo box

	data_1 = new Option("1", "$");
	data_2 = new Option("2", "$$");

// second combo box

	data_1_1 = new Option("11", "-");
	data_1_2 = new Option("12", "-");
	data_2_1 = new Option("21", "--");
	data_2_2 = new Option("22", "--");
	data_2_3 = new Option("23", "--");
	data_2_4 = new Option("24", "--");
	data_2_5 = new Option("25", "--");

// third combo box

	data_1_1_1 = new Option("111", "*");
	data_1_1_2 = new Option("112", "*");
	data_1_1_3 = new Option("113", "*");
	data_1_2_1 = new Option("121", "*");
	data_1_2_2 = new Option("122", "*");
	data_1_2_3 = new Option("123", "*");
	data_1_2_4 = new Option("124", "*");
	data_2_1_1 = new Option("211", "**");
	data_2_1_2 = new Option("212", "**");
	data_2_2_1 = new Option("221", "**");
	data_2_2_2 = new Option("222", "**");
	data_2_3_1 = new Option("231", "***");
	data_2_3_2 = new Option("232", "***");

// fourth combo box

	data_2_2_1_1 = new Option("2211","%")
	data_2_2_1_2 = new Option("2212","%%")

// other parameters

    displaywhenempty=""
    valuewhenempty=-1

    displaywhennotempty="-select-"
    valuewhennotempty=0


function change(currentbox) {
	numb = currentbox.id.split("_");
	currentbox = numb[1];

    i=parseInt(currentbox)+1

// I empty all combo boxes following the current one

    while ((eval("typeof(document.getElementById(\"combo_"+i+"\"))!='undefined'")) &&
           (document.getElementById("combo_"+i)!=null)) {
         son = document.getElementById("combo_"+i);
	     // I empty all options except the first one (it isn't allowed)
	     for (m=son.options.length-1;m>0;m--) son.options[m]=null;
	     // I reset the first option
	     son.options[0]=new Option(displaywhenempty,valuewhenempty)
	     i=i+1
    }


// now I create the string with the "base" name ("stringa"), ie. "data_1_0"
// to which I'll add _0,_1,_2,_3 etc to obtain the name of the combo box to fill

    stringa='data'
    i=0
    while ((eval("typeof(document.getElementById(\"combo_"+i+"\"))!='undefined'")) &&
           (document.getElementById("combo_"+i)!=null)) {
           eval("stringa=stringa+'_'+document.getElementById(\"combo_"+i+"\").selectedIndex")
           if (i==currentbox) break;
           i=i+1
    }


// filling the "son" combo (if exists)

    following=parseInt(currentbox)+1

    if ((eval("typeof(document.getElementById(\"combo_"+following+"\"))!='undefined'")) &&
       (document.getElementById("combo_"+following)!=null)) {
       son = document.getElementById("combo_"+following);
       stringa=stringa+"_"
       i=0
       while ((eval("typeof("+stringa+i+")!='undefined'")) || (i==0)) {

       // if there are no options, I empty the first option of the "son" combo
	   // otherwise I put "-select-" in it

	   	  if ((i==0) && eval("typeof("+stringa+"0)=='undefined'"))
	   	      if (eval("typeof("+stringa+"1)=='undefined'"))
	   	         eval("son.options[0]=new Option(displaywhenempty,valuewhenempty)")
	   	      else
	             eval("son.options[0]=new Option(displaywhennotempty,valuewhennotempty)")
	      else
              eval("son.options["+i+"]=new Option("+stringa+i+".text,"+stringa+i+".value)")
	      i=i+1
	   }
       //son.focus()
       i=1
       combostatus=''
       cstatus=stringa.split("_")
       while (cstatus[i]!=null) {
          combostatus=combostatus+cstatus[i]
          i=i+1
          }
       return combostatus;
    }
}

//-->
</script>

<form>
<select name="combo0" id="combo_0" onChange="change(this);" style="width:200px;">
	<option value="value1">-select-</option>
	<option value="value2">1</option>
	<option value="value3">2</option>

</select>
<BR><BR>
<select name="combo1" id="combo_1" onChange="change(this)" style="width:200px;">
	<option value="value1">  </option>
</select>
<BR><BR>
<select name="combo2" id="combo_2" onChange="change(this);" style="width:200px;">
	<option value="value1">  </option>
</select>
<BR><BR>
<select name="combo3" id="combo_3" onChange="change(this);" style="width:200px;">
	<option value="value1">  </option>

</select>

</form>

<option onclick="document.getElementById('second_combo_box').style.display = 'block'">...</option>

<option onclick="document.getElementById('third_combo_box').style.display = 'block'">...</option>

<slect id="first" onChage="some_function(); document.getElementById('second').style.display = 'block'">
....
</select>

<slect id="second" style="display:none" onChage="some_function(); document.getElementById('third').style.display = 'block'">
....
</select>

<slect id="third" style="display:none" onChage="some_function();">
....
</select>

<?php
    if(isset($_POST['go']))
        echo $POST['first'];
?>
<form action="" method="POST">
<slect id="first" name="first" onChage="some_function(); document.getElementById('second').style.display = 'block'">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select>
<input type="submit" name="go">
</form>

<slect id="first" name="first" onChage="some_function(); document.getElementById('second').style.display = 'block'; alert(this.options[this.selectedIndex].value)">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select>