JSFiddle - React, Tailwind, and code Playground

HTML

<select id="jform_city" class="inputbox" name="jform[city]" value="">
<option value="39001">ABERGEMENT-LA-RONCE</option>
<option value="39099">CHAMPDIVERS</option>
<option value="39189">DAMPARIS</option>
<option value="39338">MOLAY</option>
<option value="39526">TAVAUX</option>
</select>

JavaScript

function getCities()
{
	var zip = $('jform_zip').value;
	if(zip.length == 5)
	{
		var ajax_url = '<?php print JURI::base();?>index.php?option=com_bingocompany';
		var myRequest = new Request({
		    url: ajax_url,
		    method: 'post',
			data: 'task=get_cities_select&zip=' + zip,
		    onSuccess: function(responseText){
				//je detruit l'element d'origine puis j'insere le nouveau après le label
		        $('jform_city').destroy();
				var jform_city_label = $('jform_city-lbl');
				var jform_city = new Element('p', responseText);
				jform_city.inject(jform_city_label, 'after');
		    },
		    onFailure: function(){
		        //myElement.set('text', 'Sorry, your request failed :(');
				alert('pas ok');
		    }
		});
		 
		myRequest.send();
	}
}