docs: function () {
              var elem = this[0];
              // No argument, return index in parent
              if (!elem) {
                  return ( this[0] && this[0].parentNode ) ? this.first().prevAll().length : -1;
              }
  
              // Index in selector
              if (typeof elem === 'string') {
                  return indexOf.call(vQ(elem), this[0]);
              }
  
              // Locate the position of the desired element
              return indexOf.call(this,
  
                  // If it receives a vQ object, the first element is used
                  elem.constructor == vQ ? elem[0] : elem
              );
          }