JSFiddle - React, Tailwind, and code Playground
by ruder partap
HTML
<div id="login">
<form>
Name: <input type="text"></input>
<br/>
Age: <input type="text"></input>
<br/>
State: <select id="state">
<option value="A">A</option>
<option value="B">B</option>
<option value="C">C</option>
<option value="D">D</option>
</select>
<br/><div id="regionArea">
Region: <select id="region">
<option value="north">North</option>
<option value="south">South</option>
</select></div>
</form>
</div>
JavaScript
$('#regionArea').hide();
$('#state').on('change', function() {
var state= $('#state').val();
if(state=="A"||state=="B"){
$('#regionArea').show();
}else{
$('#regionArea').hide();
}
})