[Сергей Ракипов]

let imgArticle = document.querySelector(".img_article");
let imgArticle_2 = document.querySelector(".img_article_2");
let explanation = document.querySelector(".explanation_defolt");

function explanationSticky(){

let scrollTop;
if (window.pageYOffset){
    scrollTop = window.pageYOffset;
}
else {
    if (document.documentElement.scrollTop){
        scrollTop = document.documentElement.scrollTop;
    }
    else{
        scrollTop = document.body.scrollTop;
    }
}

function myFunction(x){
	if(x.matches){
		if(scrollTop >= 220 & scrollTop <= 820){
			explanation.classList.remove("explanation_defolt");
			explanation.classList.add("explanation_scroll");
		}
		else{
			explanation.classList.add("explanation_defolt");
			explanation.classList.remove("explanation_scroll");
		}
	}
	else{
		explanation.classList.remove("explanation_scroll");
		explanation.classList.remove("explanation_defolt");
		explanation.classList.add("explanation_mobile");
	}
}

let x = window.matchMedia("(max-width: 860px)");
myFunction(x);
x.addListener(myFunction);

window.addEventListener("scroll", explanationSticky);

У меня
Unexpected end of input в последней строке
и правильно ли соблюден синтаксис