Dropdown where you can select a pre-existing option, or "other" and create your own

dropdown.html

<select onchange="checkvalue(this.value)">
    <option value='Bailey'>Bailey</option>
    <option value='Bedichek'>Bedichek</option>
    <option value='Burnet'>Burnet</option>
    <option selected value="Other">Other</option>
</select>
<input type="text" name="current_school_other" id="other_current_school" class="pad" style='visibility:visible;' disabled/>
 
<script>
function checkvalue(val) {
    if(val == "Other") {
        document.getElementById("other_current_school").style.visibility='visible';
    } else {
        document.getElementById("other_current_school").style.visibility='hidden';
    }
}
</script>