[рони]

MaJIon,

let ajax;
$('.btn-slide').click(function() {
if(!ajax) $.ajax({
        url: 'index.php?route=/menu',
        type: 'POST',
        dataType: 'html',
        beforeSend: function() {
            $('.loaders').addClass('active');
            $("#panel").slideToggle("slow");
            ajax = true;
        },
        success: function(htmlText) {
            $('.loaders').removeClass('active');
            $('#panel').html(htmlText);
        }
    });
else $("#panel").slideToggle("slow");