regimenten.js

<script type="text/javascript">
    function Dropdown(eenheid,regimenten) {
    var A.B.L = <?php json_encode($Regimenten_ABL); ?>

    switch (eenheid.value) {
        case 'A.B.L':
            regimenten.options.length = 0;
            for (i = 0; i < colours.length; i++) {
                createOption(regimenten, A.B.L[i], A.B.L[i]);
            }
            break;
            default:
                regimenten.options.length = 0;
            break;
    }

}

    function createOption(ddl, text, value) {
        var opt = document.createElement('option');
        opt.value = value;
        opt.text = text;
        ddl.options.add(opt);
    }
</script>

<select id="eenheid" onchange="Dropdown(this,document.getElementById('regimenten'))">
<option value="A.B.L">Belgisch Militair</option>
</select>

<select class="from-control "id="regimenten">
</select>