<li><span class="search-btn">Поиск</span></li>

<div class="main-search search-btn">

.search-btn {
  width: 20px;
  height: 20px;
  background: #e6e6e6;
}

const SearchBtn = document.querySelectorAll(".search-btn");
sSearchBar = document.querySelector("#search-bar");



for (var i = 0; i < SearchBtn.length; i++) {
  SearchBtn[i].addEventListener("click", event => {
    alert(1);
  sSearchBar.classList.toggle("active");
  sidebarBox.classList.remove("active");
  regbar.classList.remove("active");
  });
  
}