JSFiddle - React, Tailwind, and code Playground

by tea4two

HTML

<select name="" id="select">
    <option value="10">10歳以下</option>
    <option value="30">11~30歳</option>
    <option value="50">31~50歳</option>
    <option value="51">51歳以上</option>
</select>

JavaScript

var select = document.getElementById('select');

select.addEventListener('change',function() {
    var age = select.value;
    switch ( age ) {
        case '10': alert('10歳'); break;
    }
    
}, false);