JSFiddle - React, Tailwind, and code Playground

HTML

<form>
	<select name="dep">
		<option>Department</option>
		<option>Sales</option>
		<option>Support</option>
	</select>
	<select name="cname">
		<option>Contact name</option>
	</select>
</form>

JavaScript

$(document).ready(function() {
$department = $("select[name='dep']");
$cname = $("select[name='cname']");

$department.change(function() {

if ($(this).val() == "Sales") {
$("select[name='cname'] option").remove();
$("<option>John Smith</option>").appendTo($cname);
$("<option>Marry Jones</option>").appendTo($cname);
}

if ($(this).val() == "Support") 
{
$("select[name='cname'] option").remove();
$("<option>Jessy McBeth</option>").appendTo($cname);
$("<option>Bob Smith</option>").appendTo($cname);
}

if ($(this).val() == "Department") 
{
$("select[name='cname'] option").remove();
$("<option>Contact name</option>").appendTo($cname);
}

});
});