javascript scroll関数

function customScroll(obj) {
  var scrObj = obj;
  var perScrollTop = 0;

  $(window).scroll(function() {
    var scrollTop = $(window).scrollTop();

    if (perScrollTop < scrollTop && perScrollTop - scrollTop <= -3 && scrObj.scrollDown !== undefined) {
      //   
      scrObj.scrollDown();
    }
    if (perScrollTop > scrollTop && perScrollTop - scrollTop >= 3 && scrObj.scrollUp !== undefined) {
      //   
      scrObj.scrollUp();
    }
    if (scrollTop > scrObj.data.topScrollPosition ? scrObj.data.topScrollPosition : null && scrObj.topScrollPosition !== undefined) {
      //                   
      scrObj.topScrollPosition();
    }
    if (scrollTop > scrObj.data.topHidePosition ? scrObj.data.topHidePosition : null && scrObj.topHidePosition !== undefined) {
      //                   
      scrObj.topHidePosition();
    }
    perScrollTop = scrollTop;
  }).on("resize.scroll", function() {
    //     
    scrObj.resizeScroll();
  });
}

//     
var scroll = new customScroll({
  'data': {
    'topScrollPosition': 600,
    'bottomScrollPosition': 600
  },
  'scrollDown': function() {
    console.log('  ')
  },
  'scrollUp': function() {
    console.log('  ')
  },
  'topScrollPosition': function() {
    console.log('                  ')
  },
  'bottomScrollPosition': function() {
    console.log('                  ')
  },
  'resizeScroll': function() {
    console.log('    ');
  }
});