Find the next or the previous instance for a given selected range

dom_element_find.js

jQuery.fn.elementAfter = function(other) {
  for(i = 0; i < this.length - 1; i++) {
    if (this[i]() == other) {
      return jQuery(this[i + 1]());
    }
  }
};

jQuery.fn.elementBefore = function(other) {
  if (this.length > 0) {
    for(i = 1; i < this.length; i++) {
      if (this[i]() == other) {
        return jQuery(this[i - 1]());
      }
    }
  }
};