code: function (checker) {
              if (isFunction(checker)) {
                  this.options.actionChecker = checker;
  
                  return this;
              }
  
              if (checker === null) {
                  delete this.options.actionChecker;
  
                  return this;
              }
  
              return this.options.actionChecker;
          }
docs: /*\
  Interactable.actionChecker
  [ method ]
  
  Gets or sets the function used to check action to be performed on
  pointerDown
  
  - checker (function | null) #optional A function which takes a pointer event, defaultAction string, interactable, element and interaction as parameters and returns an object with name property 'drag' 'resize' or 'gesture' and optionally an `edges` object with boolean 'top', 'left', 'bottom' and right props.
  = (Function | Interactable) The checker function or this Interactable
  
  | interact('.resize-drag')
  |   .resizable(true)
  |   .draggable(true)
  |   .actionChecker(function (pointer, event, action, interactable, element, interaction) {
  |
  |   if (interact.matchesSelector(event.target, '.drag-handle') {
  |     // force drag with handle target
  |     action.name = drag;
  |   }
  |   else {
  |     // resize from the top and right edges
  |     action.name  = 'resize';
  |     action.edges = { top: true, right: true };
  |   }
  |
  |   return action;
  | });
  \