Nothing I've found here and on the web works on the website http://lexic-on.ru/ru/ (Joomla based) I tried to use this solution Change Active Menu Item on Page Scroll? but it didn't work
UPD:
I put the exact JS code
<script type='text/javascript'>//<![CDATA[
$(window).load(function(){
// Cache selectors var lastId, topMenu = $("#sp-main-menu")
----> my menu id
.......
.end().filter("[href=#"+id+"]").parent().addClass("active");
}
});
});//]]>
</script>
as well as jquery 2.3.1 link from Google in the head
Menu looks like this:
<div id="sp-main-menu" class="visible-desktop">
<ul class="sp-menu level-0"><li class="menu-item active first">
....<a href="#services" class="menu-item" ><span class="menu"><span class="menu-title">Услуги</span></span></a></li>
.....
It works perfectly on a test page without other scripts. But nothing works on the site. I guess some other script conflicts with this one.