Function to initialize buttonDropdowns in Ecwid CSS Framework

buttonDropdowns.js

function buttonDropdowns() {
    btnDropdowns = document.querySelectorAll(".btn-dropdown");

    for (var i = 0; i < btnDropdowns.length; i++) {
        if (btnDropdowns[i].addEventListener) {
            btnDropdowns[i].addEventListener("click", function(e) {
                showDropdown(this);
                e.stopPropagation();
            });
        } else {
            btnDropdowns[i].attachEvent("onclick", function(e) {
                showDropdown(this)
                e.stopPropagation();
            });
        }
    }

    function showDropdown(obj) {
        isActive = obj.parentNode.classList.contains('opened');
        closeDropdowns();

        if (!isActive) {
            obj.parentNode.classList.add('opened');
            isActive = true;
        }
    }

    function closeDropdowns() {
        for (var i = 0; i < btnDropdowns.length; i++) {
            if (btnDropdowns[i].parentNode.classList.contains('opened')) {
                btnDropdowns[i].parentNode.classList.remove('opened');
            }
        }
    }

    if (document.addEventListener) {
        document.addEventListener("click", function(e) {
            if (!e.target.classList.contains('btn-dropdown')) {
                closeDropdowns();
            }
        });
    } else {
        document.attachEvent("click", function(e) {
            if (!e.target.classList.contains('btn-dropdown')) {
                closeDropdowns();
            }
        });
    }
}