getElementsByClassName function. Provides a fallback for legacy browsers that do not support the native HTML5 DOM method.

getElementsByClassName function

function getElementsByClassName(node, className) {
  if (node.getElementsByClassName) {
    return node.getElementsByClassName(className);
  } else {
    var results = [];
    var elems = node.getElementsByTagName("*");
    for (var i = 0, len = elems.length; i < len; i++) {
      if (elems[i].className.indexOf(className) != -1) {
        results.push(elem[i]);
      }
    }
    return results;
  }
}