Customer service decision tree in javascript

decisionTree.js

<script>
    $(document).ready( function () {
        $('#customerTripsTable').DataTable();
        $('#customerNotesTable').DataTable();
    } );
    //reset all children nodes in tree if the parent is clicked
    document.getElementById("contacttype").onclick = destroyChildren;
    //listener for contact type dropdown
    document.getElementById("contacttype").onchange = function() {
        var selected = document.getElementById("contacttype").value;
        if(selected == 'initial'){
            //alert(selected);
            // display another dropdown
            document.getElementById("initial").style.display ='block';
        }
        else if(selected == 'incoming'){
            showNotesField();
        }
        else if(selected == 'outgoing'){
            document.getElementById("outgoing").style.display ='block';
            showNotesField();
        }
        else if(selected == 'custom'){
            showNotesField();
        }
        else{
            alert('error');
        }
    }

    //listener for INITIAL contact dropdown
    document.getElementById("initial_contact").onchange = function(){
        var selected = document.getElementById("initial_contact").value;
        if(selected == 'vm'){
            document.getElementById("how_you_heard").style.display ='none';
            removeNotesField();
        }
        else if (selected == 'telephone' ||
                selected == 'email' ||
                selected == 'text')
        {
            document.getElementById("how_you_heard").style.display ='block';
            showNotesField();
        }
    }

    /**
     * Destroys children nodes if the decision tree is changed
     */
    function destroyChildren(){
        document.getElementById("initial").style.display ='none';
        document.getElementById("outgoing").style.display ='none';
        document.getElementById("how_you_heard").style.display ='none';
        removeNotesField();
    }
    /**
     * Reveals the contact notes field
     */
    function showNotesField(){
        document.getElementById("notes").style.display ='block';
    }
    /**
     * Hides the contact notes field
     */
    function removeNotesField(){
        document.getElementById("notes").style.display ='none';
    }
    /**
     * Ajax request to call process that resets customer password and sends them a new password via email
     */
    function resetPassword(){
        if(confirm('Are you sure you want to reset?')){
            $.ajax
            ({
                url: 'php/doResetCustomerPassword.php',
                type: 'post',
                success: function(data)
                {
                   if(data){
                       alert("Reset!");
                   }
                    else {
                       alert("Password NOT reset");
                   }
                }
            });
        }
    };

</script>