Nodejs Utililty Methods HTML Element Class Check

Element.prototype.hasClass = function (classname) {
    if (this == null) throw new TypeError();
    return this.className.split(' ').indexOf(classname) === -1 ? false : true;

Element.prototype.hasClass = function(cls) {
  return this.className.match(new RegExp('(\\s|^)'+cls+'(\\s|$)'));
};

Element.prototype.hasClass=function(selector){
  if((" " + this.className + " ").replace(/[\n\t]/g, " ").indexOf(" " + selector + " ") > -1 ){
    return true;
  return false;
};

Element.prototype.hasStyleClass = function(className) {
    if (!className)
        return false;
    if (this.className === className)
        return true;
    var regex = new RegExp("(^|\\s)" + className.escapeForRegExp() + "($|\\s)");
    return regex.test(this.className);
};

HTMLElement.prototype.classContains = function() {
  var args = arguments;
  if (args.length < 1) {
    return false;
  for (var i = 0; i < args.length; i++) {
    var classList = this.classList;
    if (!classList.contains(args[i])) {
      return false;
...

Element.prototype.is = function(elementSelector) {
  switch (elementSelector[0]) {
    case '.':
      var er = new RegExp(elementSelector.replace('.', ''))
      return this.className.match(er)
      break
    case '#':
      return this.getAttribute('id') === elementSelector.replace('#', '')
      break
...