javascript class click event
var elements = document.getElementsByClassName("classname");
var myFunction = function() {
    var attribute = this.getAttribute("data-myattribute");
    alert(attribute);
};
for (var i = 0; i < elements.length; i++) {
    elements[i].addEventListener('click', myFunction, false);
}
// If you have ES6 support you can replace your last line with:
    Array.from(elements).forEach(function(element) {
      element.addEventListener('click', myFunction);
    });