Wie schalte ich mit JavaScript die Sichtbarkeit mehrerer HTML-Elemente nach Klassennamen um?

function getElementsByClassName(node, className) {
  if (node.getElementsByClassName) {
    // Native implementation available
    return node.getElementsByClassName(className);
  } else {
    // Use fallback method
    return (function getElementsByClass(searchClass, node) {
      if (!node) node = document;
      var classElements = [],
          els = node.getElementsByTagName("*"),
          pattern = new RegExp("(^|\s)" + searchClass + "(\s|$)");

      for (var i = 0, j = 0; i < els.length; i++) {
        if (pattern.test(els[i].className)) {
          classElements[j] = els[i];
          j++;
        }
      }
      return classElements;
    })(className, node);
  }
}

function toggleVisibility(className) {
   var elements = getElementsByClassName(document, className),
       n = elements.length;
   for (var i = 0; i < n; i++) {
     var e = elements[i];

     if (e.style.display == 'block') {
       e.style.display = 'none';
     } else {
       e.style.display = 'block';
     }
  }
}