<li class="menu_catalog" onclick="click_menu('catalog')"><a href="#content">Каталог лазеров</a></li>

function click_menu(){
var url_adress= '12';
var css= '12';
var name= '12';
var sub_name= '12';
if ('catalog'){
    var url_adress='catalog.html';
    var css= 'catalog.css';
    var name= 'Каталог';
};
console.log(25);
$('#content').load('./pages/products/'+url_adress);
$('link:last').attr('href', 'css/'+css);
$('.active').html(name);}