This question has been answered by Jul. See the first response.
<img id="mainPicture" src="" alt="" /> [!easy2? &gid=`[*id_galerie*]` !]
<script type="text/javascript"> jQuery(document).ready(function(){ // Set main picture from path of thumbnail function SetMainPicture (src) { var ext = src.slice(src.lastIndexOf('.')); src = src.replace("_thumbnails/", ""); var parts = src.split("_"); src = parts.splice(0,parts.length-3).join("_"); src= src+ext; jQuery("#mainPicture").attr('src',src); return; } // Initialize main picture jQuery("div.boxcontent:first").each(function () { var thumb = jQuery(this).find("img"); var src = thumb.attr("src"); SetMainPicture(src); }); // Load the picture corresponding to the clicked thumbnail jQuery("div.boxcontent","div.thumb").click( function() { var thumb = jQuery(this).find("img"); var src = thumb.attr("src"); SetMainPicture(src); }) }); </script>