JSFiddle - React, Tailwind, and code Playground

by int32_t

HTML

<select multiple>
    <option>1</option>
    <option>2</option>
    <option>3</option>
</select>
<br>
<button>Unselect</button>
<hr>
<div id=console></div>

JavaScript

function log(str) {
    var c = document.getElementById('console');
    c.appendChild(document.createTextNode(str));
    c.appendChild(document.createElement('br'));
}
function dumpState(s) {
    var o = s.options;
    for (var i = 0; i < o.length; ++i)
        log('options[' + i + ']: ' + o[i].selected);
}

var s = document.querySelector('select');
dumpState(s);
document.querySelector('button').addEventListener('click', function() {
    log('');
    log('Unselect the first option');
    s.options[0].selected = false;
    dumpState(s);
}, false);