vanilla javascript toggleClass

toggleClass.js

function toggleClass(element, className) {
  if (!element || !className) { return; }
  var classString = element.className, nameIndex = classString.indexOf(className);
  if (nameIndex == -1) {
    classString += (classString.length) ? ' ' + className : className;
  } else {
    classString = classString.replace(' '+className, '');
    classString = classString.replace(className, '');
  }
  element.className = classString;
}