scrollFire.js

(function($) {

  // Input: Array of JSON objects {selector, offset, callback}

  Materialize.scrollFire = function(options) {

    var didScroll = false;

    window.addEventListener("scroll", function() {
      didScroll = true;
    });

    // Rate limit to 100ms
    setInterval(function() {
        if(didScroll) {
            didScroll = false;

            var windowScroll = window.pageYOffset + window.innerHeight;

            for (var i = 0 ; i < options.length; i++) {
              // Get options from each line
              var value = options[i];
              var selector = value.selector,
                  offset = value.offset,
                  callback = value.callback;

              var currentElement = document.querySelector(selector);
              if ( currentElement !== null) {
                var elementOffset = currentElement.getBoundingClientRect().top + document.body.scrollTop;

                if (windowScroll > (elementOffset + offset)) {
                  if (value.done != true) {
                    var callbackFunc = new Function(callback);
                    callbackFunc();
                    value.done = true;
                  }
                }
              }
            };
        }
    }, 100);


    // $(window).scroll(function () {
    //   var windowScroll = $(window).scrollTop() + $(window).height();

    //   $.each( options, function( i, value ){
    //     var selector = value.selector,
    //         offset = value.offset,
    //         callback = value.callback;

    //     if ($(selector).length != 0) {
    //       var elementOffset = $(selector).offset().top;

    //       if (windowScroll > (elementOffset + offset)) {
    //         if (value.done != true) {
    //           var callbackFunc = new Function(callback);
    //           callbackFunc();
    //           value.done = true;
    //         }
    //       }
    //     }

    //   });
    // });

  }

})(jQuery);