JSFiddle - React, Tailwind, and code Playground

HTML

<div id="mapContainer"><iframe width="425" height="350" frameborder="0" scrolling="no" marginheight="0" marginwidth="0" src="https://maps.google.it/maps?f=q&amp;source=s_q&amp;hl=it&amp;geocode=&amp;q=Milano&amp;aq=&amp;sll=45.52498,9.230734&amp;sspn=0.215275,0.528374&amp;ie=UTF8&amp;hq=&amp;hnear=Milano,+Lombardia&amp;ll=45.524871,9.230576&amp;spn=0.215503,0.528374&amp;t=m&amp;z=12&amp;output=embed"></iframe></div>
<br />
<input type="text" placeholder="Indirizzo di partenza" class="startMap" /><input class="updateMap" type="button" value="Ottieni indicazioni" />

JavaScript

// Al click sul bottone...
$(".updateMap").click(function () {
    
    // Indico indirizzo di destinazione
    var endMap = "Milano";
    // Ottengo indirizzo di partenza
    var startMap = $(".startMap").val();
    // Genero URL Google Maps
    var urlMap = "https://maps.google.com/maps?saddr=%22" + startMap + "%22&daddr=%22" + endMap + "%22&t=h&t=m";
    // Ricreo l'iframe con la nuova mappa
    $("#mapContainer").html('<iframe width="425" height="350" frameborder="0" scrolling="no" marginheight="0" marginwidth="0" src="' + urlMap + '&output=embed"></iframe><br><a href="' + urlMap + '">Guarda le indicazioni complete</a>' );

});