Why can't I insert a function into the callback?

Question

JavaScript

I'm trying to insert a function call into the callback viewportChecker

$('div').viewportChecker({
      classToAdd: 'visible',
      classToRemove: 'invisible',
      invertBottomOffset: true,
      repeat: false,
      callbackFunction: function(elem, action){
                  anyFunction();
       }, // 
      scrollHorizontal: false
  });

And every time I get "is not a function" , outside the callback everything works fine. What could it be?

Answer 1

offset - The delay in the appearance of elements, relative to the viewport. Specified as a number (value in pixels). You can specify a percentage (specify in quotes, with the "%" sign )