JSFiddle - React, Tailwind, and code Playground

HTML

<select id="myselect" multiple="multiple">
<option value="0">0-0-0-0-0-0</option>
<option value="1">1-1-1-1-1-1</option>
<option value="2">2-2-2-2-2-2</option>
<option value="3">3-3-3-3-3-3</option>
<option value="4">4-4-4-4-4-4</option>
</select>

JavaScript

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

function processChange(event) {
    var selectElement = event.target;
    
    console.log(selectElement.selectedOptions);
}

select.addEventListener('change', processChange);