JSFiddle - React, Tailwind, and code Playground
by TCHdevlp
HTML
<select name="test.machin.truc" id="test.machin.truc">
<option value="1">Un</option>
<option value="2">Deux</option>
<option value="3">Trois</option>
</select>
<input type="button" value="test" id="boutontest"/>
JavaScript
$("#boutontest").click(function(){
$('select[name="test.machin.truc"]').val('3');
});