[ jQuery ] Scroll to anchor link and offset based on header height

script.js

(function ($) {
  $("a[href*=\\#]:not([href=\\#])").click(function () {
    if (
      location.pathname.replace(/^\//, "") ==
        this.pathname.replace(/^\//, "") ||
      location.hostname == this.hostname
    ) {
      var target = $(this.hash),
        headerHeight = $("header#site-header").height() + 20;

      target = target.length ? target : $("[name=" + this.hash.slice(1) + "]");

      if (target.length) {
        $("html,body").animate(
          {
            scrollTop: target.offset().top - headerHeight,
          },
          500
        );
        return false;
      }
    }
  });
})(jQuery);