before

This method can be used to insert an element or HTML string before each element in the collection.

// Insert an element before the elements
before: function(element) {
  this.elements.forEach(function(el) {
    el.parentNode.insertBefore(element, el);
  });
  return this;
},
 
// Insert an HTML string before the elements
before: function(html) {
  this.elements.forEach(function(el) {
    el.insertAdjacentHTML("beforebegin", html);
  });
  return this;
}

Append Prepend