JSFiddle - React, Tailwind, and code Playground

by chen jian

HTML

<select id="Main_body">
<option value="1">Alpha</option>
<option value="2">Beta</option>
</select>

<select id="Sub1">
<option value="11">Omega</option>
<option value="12">Gamma</option>
</select>

<select id="Sub2">
<option value="21">Foxtrot</option>
<option value="22">Kilo</option>
</select>

JavaScript

var sub1=document.getElementById("Sub1"),
    sub2=document.getElementById("Sub2"),
    Main_body = document.getElementById("Main_body");
sub2.style.display = 'none';
Main_body.onchange = function (){
    if(this.value == 1){
        sub2.style.display = 'none';
        sub1.style.display = 'inline-block';
    }else{
        sub1.style.display = 'none';
        sub2.style.display = 'inline-block';
    }
};