JSFiddle - React, Tailwind, and code Playground

HTML

<script>
function Selected(a) {
        var label = a.value;
        if (label==1) {
            document.getElementById("Block1_moscow").style.display='block';
            document.getElementById("Block2_voronej").style.display='none'; 
            document.getElementById("Block3_nn").style.display='none'; 
            document.getElementById("Block4_piter").style.display='none'; 
        } else if (label==2) {
            document.getElementById("Block1_moscow").style.display='none';
            document.getElementById("Block2_voronej").style.display='block'; 
            document.getElementById("Block3_nn").style.display='none'; 
            document.getElementById("Block4_piter").style.display='none';  
		} else if (label==3) {
            document.getElementById("Block1_moscow").style.display='none';
            document.getElementById("Block2_voronej").style.display='none'; 
            document.getElementById("Block3_nn").style.display='block'; 
            document.getElementById("Block4_piter").style.display='none';  
		} else if (label==4) {
            document.getElementById("Block1_moscow").style.display='none';
            document.getElementById("Block2_voronej").style.display='none'; 
            document.getElementById("Block3_nn").style.display='none'; 
            document.getElementById("Block4_piter").style.display='block';  
        }
}
</script>


<select name="Ваш город" size="1" id="gorod" onchange="Selected(this)">
<option>Ваш город</option>
<option value="1">Москва</option>
<option value="2">Воронеж</option>
<option value="3">Нижний Новгород</option>
<option value="4">Санкт-Петербург</option>
</select>

<div id='Block1_moscow'>
<iframe name="ya_map_moscow" id="ya_map_moscow" src="http://maps.yandex.ru"></iframe>
</div>
<div id='Block2_voronej' style='display: none;'>
<iframe name="ya_map_voronej" id="ya_map_voronej"...