JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html>
<body>

<form action="">
<select id="service" name="service" multiple>
  <option value="Cardio">Cardiologie</option>
  <option value="Neuro">Neurologie</option>
  <option value="Gyneco">Gynecologie</option>
  <option value="Trauma">Traumatologie</option>
</select>
<input type="button" value="selectionner" onclick="selection_service();">
</form>

<p id="ma_selection"></p>

</body>
</html>

JavaScript

selection_service = function(){
console.log('coucou', $('#service').find('option:selected'));
	$('#ma_selection').html('');
  $('#service').find('option:selected').each(function(){
  	$('#ma_selection').append($(this).val() + '<br>');
  });
}