If you use dot net core 3.1, it is supporting case ignore route, so the previous way is not helpful if the rout is in small letters and the user writes the rout in capital letters.
So, the following code is very helpful:
$(document).ready(function () {
$("div.sidebar nav a").removeClass("active");
var urlPath = window.location.pathname.split("?")[0];
var nav = $('div.sidebar nav a').filter(function () {
return $(this).attr('href').toLowerCase().indexOf(urlPath.toLocaleLowerCase()) > -1;
});
$(nav).each(function () {
if ($(this).attr("href").toLowerCase() == urlPath.toLocaleLowerCase())
$(this).addClass('active');
});
});