1n3gan,
попробуйте заменить ваш плагин
<script src="jquery.singlePageNav.min.js"></script>
на код ниже
<script>"function"!==typeof Object.create&&(Object.create=function(c){function f(){}f.prototype=c;return new f}); (function(c,f,h,k){var g={init:function(a,b){this.options=c.extend({},c.fn.singlePageNav.defaults,a);this.container=b;this.$container=c(b);this.$links=this.$container.find("a");""!==this.options.filter&&(this.$links=this.$links.filter(this.options.filter));this.$window=c(f);this.$htmlbody=c("html, body");this.$links.on("click.singlePageNav",c.proxy(this.handleClick,this));this.didScroll=!1;this.checkPosition();this.setTimer()},handleClick:function(a){var b=this,d=a.currentTarget,e=c(d.hash);a.preventDefault(); e.length&&(b.clearTimer(),"function"===typeof b.options.beforeStart&&b.options.beforeStart(),b.setActiveLink(d.hash),b.scrollTo(e,function(){b.options.updateHash&&history.pushState&&history.pushState(null,null,d.hash);b.setTimer();if("function"===typeof b.options.onComplete)b.options.onComplete()}))},scrollTo:function(a,b){var c=this.getCoords(a).top,e=!1;this.$htmlbody.stop().animate({scrollTop:c},{duration:this.options.speed,easing:this.options.easing,complete:function(){"function"!==typeof b|| e||b();e=!0}})},setTimer:function(){var a=this;a.$window.on("scroll.singlePageNav",function(){a.didScroll=!0});a.timer=setInterval(function(){a.didScroll&&(a.didScroll=!1,a.checkPosition())},250)},clearTimer:function(){clearInterval(this.timer);this.$window.off("scroll.singlePageNav");this.didScroll=!1},checkPosition:function(){var a=this.$window.scrollTop(),a=this.getCurrentSection(a);this.setActiveLink(a)},getCoords:function(a){return{top:Math.round(a.offset().top)-this.options.offset}},setActiveLink:function(a){a= this.$container.find("a[href='"+a+"']");a.hasClass(this.options.currentClass)||(this.$links.removeClass(this.options.currentClass),a.addClass(this.options.currentClass),a.trigger("click"))},getCurrentSection:function(a){var b,d,e,f;for(b=0;b<this.$links.length;b++)d=this.$links[b].hash,c(d).length&&(e=this.getCoords(c(d)),a>=e.top-this.options.threshold&&(f=d));return f||this.$links[0].hash}};c.fn.singlePageNav=function(a){return this.each(function(){Object.create(g).init(a,this)})};c.fn.singlePageNav.defaults= {offset:0,threshold:120,speed:400,currentClass:"current",easing:"swing",updateHash:!1,filter:"",onComplete:!1,beforeStart:!1}})(jQuery,window,document);</script>
напишите получился ли тот эффект который вы хотели.
