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so I've been working on this watching tutorials and such, but ran into a problem and need help. So i have a dropdown list that populates another dropdown list successfully. The problem is that I am creating the 2nd dropdown list to be populated, but want to populate an existing dropdownlist. Could anybody give me any advice on how to do this if I did not create the 2nd dropdown list and already had one(so it would populate the 2nd dropdown list which would already exist)?

Here is what I have:

<!DOCTYPE HTML>
<html>
<head>
</head>
<body>

<form name="form1" action="submit.php" method='POST'>


<select name="country" onchange="window.getStates()">
        <option value="">Select State</option>
        <option value="louisiana">Louisiana</option>
        <option value="texas">Texas</option>
        <option value="alabama">Alabama</option>
        <option value="mississippi">Mississippi</option>
    </select>

    <input type="submit" name="submit" value="Submit">
</form>

<script type="text/javascript">
    function getStates()
    {
        var xmlhttp;
        try{
            xmlhttp = new XMLHttpRequest;
           }catch(e)
           {
            xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
               }

        if(xmlhttp)
            {
                var form = document['form1'];
                var country = form['country'].value;

                xmlhttp.open("GET", "getScools.php?country="+country, true);

                xmlhttp.onreadystatechange = function ()
                {
                    if(this.readyState == 4)
                    {
                        var s = document.createElement("select");
                        s.name= "state";
                        s.innerHTML = this.responseText;

                        if(form['state'])
                        {
                            form.replaceChild(s, form['state']);
                        }else
                            form.insertBefore(s, form['submit']);
                    }
                }                   

                xmlhttp.send(null)
            }
    }

</script>

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