whole_func_string: function listener(element, selector, type, callback) {
      return function(e) {
          e.delegateTarget = closest_1(e.target, selector);
  
          if (e.delegateTarget) {
              callback.call(element, e);
          }
      }
  }
func_code_string: function listener(element, selector, type, callback) {
      return function(e) {
          e.delegateTarget = closest_1(e.target, selector);
  
          if (e.delegateTarget) {
              callback.call(element, e);
          }
      }
  }
func_documentation_string: Finds closest match and invokes callback.
  
  @param {Element} element
  @param {String} selector
  @param {String} type
  @param {Function} callback
  @return {Function}