Get Elements by Clazz

gebc.js

var getEByClass = function (_) {
  var regExp = new RegExp("\\b" + _ + "\\b", ""),
    elements = [];
      
  var clazz = function (e) {
    return e.className || "";
  };
  
  var getAll = function (context) {
    var c = clazz(context);
    if (c !== "" && c.match(regExp)) {
      elements.push(context);
    }
    var children = context.childNodes;
    for (var o in children) {
      var e = children[o];
      if (e.nodeType !== Node.ELEMENT_NODE) {
          continue;
      }
      getAll(e);
    }
  };

  var s = document.getElementsByTagName('html')[0];
  if (s) {
    getAll(s);
  }

  return elements;
};

// Crockford
function walkTheDOM(node, func) {
  func(node);
  node = node.firstChild;
  while (node) {
    walkTheDOM(node, func);
    node = node.nextSibling;
  }
}

function getElementsByClassName(className) {
  var results = [];
  walkTheDOM(document.body, function (node) {
    var a, c = node.className,
      i;
    if (c) {
      a = c.split(' ');
      for (i = 0; i < a.length; i++) {
        if (a[i] === className) {
          results.push(node);
          break;
        }
      }
    }
  });
  return results;
}