Scrolling lock JavaScript.

lock.js

// VARIABLES
var counter = 1;
var scrollDirection;
var slides = $('#main div');
var slidesLength = slides.length;
var inTransition = false;

// SCROLL DISTANCES 
function scrollAnimate(distance){
  inTransition = true;
  $('#main').css('transform','translate3d(0,' + distance + '%,0)');
  setTimeout(function(){
    inTransition = false;
  }, 1300);
};

// SCROLL ANIMATIONS AND LOGIC
function scrollLogic(){
  //---------------- DOWN TRANSITIONS ----------------------------
  // SLIDE 1 --> SLIDE 2
  if( counter == 1 && scrollDirection == "down" ){
    scrollAnimate(-20);
  }

  // SLIDE 2 --> SLIDE 3
  else if( counter == 2 && scrollDirection == "down" ){
    scrollAnimate(-40);
  } 

  // SLIDE 3 --> SLIDE 4
  else if( counter == 3 && scrollDirection == "down" ){
    scrollAnimate(-60);
  } 

  // SLIDE 3 --> SLIDE 4
  else if( counter == 4 && scrollDirection == "down" ){
    scrollAnimate(-80);
  }

  //---------------- UP TRANSITIONS ----------------------------
  // SLIDE 5 --> SLIDE 4
  else if( counter == 5 && scrollDirection == "up" ){
    scrollAnimate(-60);
  }

  // SLIDE 4 --> SLIDE 3
  else if( counter == 4 && scrollDirection == "up" ){
    scrollAnimate(-40);
  }

  // SLIDE 3 --> SLIDE 2
  else if( counter == 3 && scrollDirection == "up" ){
    scrollAnimate(-20);
  }

  // SLIDE 2 --> SLIDE 1
  else if( counter == 2 && scrollDirection == "up" ){
    scrollAnimate(0);
  }

  else{
    inTransition = false;
  };

  //---------------- UPDATE COUNTER ----------------------------
  if( scrollDirection == "down" && counter < slidesLength ){
    counter++;
  } else if( scrollDirection == "up" && counter > 1 ){
    counter--;
  };
};

// creates a global "addWheelListener" method
(function(window,document) {

    var prefix = "", _addEventListener, onwheel, support;

    // detect event model
    if ( window.addEventListener ) {
        _addEventListener = "addEventListener";
    } else {
        _addEventListener = "attachEvent";
        prefix = "on";
    }

    // detect available wheel event
    support = "onwheel" in document.createElement("div") ? "wheel" : // Modern browsers support "wheel"
              document.onmousewheel !== undefined ? "mousewheel" : // Webkit and IE support at least "mousewheel"
              "DOMMouseScroll"; // let's assume that remaining browsers are older Firefox

    window.addWheelListener = function( elem, callback, useCapture ) {
        _addWheelListener( elem, support, callback, useCapture );

        // handle MozMousePixelScroll in older Firefox
        if( support == "DOMMouseScroll" ) {
            _addWheelListener( elem, "MozMousePixelScroll", callback, useCapture );
        }
    };

    function _addWheelListener( elem, eventName, callback, useCapture ) {
        elem[ _addEventListener ]( prefix + eventName, support == "wheel" ? callback : function( originalEvent ) {
            !originalEvent && ( originalEvent = window.event );

            // create a normalized event object
            var event = {
                // keep a ref to the original event object
                originalEvent: originalEvent,
                target: originalEvent.target || originalEvent.srcElement,
                type: "wheel",
                deltaMode: originalEvent.type == "MozMousePixelScroll" ? 0 : 1,
                deltaX: 0,
                delatZ: 0,
                preventDefault: function() {
                    originalEvent.preventDefault ?
                        originalEvent.preventDefault() :
                        originalEvent.returnValue = false;
                }
            };
            
            // calculate deltaY (and deltaX) according to the event
            if ( support == "mousewheel" ) {
                event.deltaY = - 1/40 * originalEvent.wheelDelta;
                // Webkit also support wheelDeltaX
                originalEvent.wheelDeltaX && ( event.deltaX = - 1/40 * originalEvent.wheelDeltaX );
            } else {
                event.deltaY = originalEvent.detail;
            }

            // it's time to fire the callback
            return callback( event );

        }, useCapture || false );
    }

})(window,document);


// LISTEN FOR WHEEL SCROLL 
addWheelListener( document.body, function(e) { 

  if (inTransition){
    return;
  };

  // DETERMINE WHEEL scrollDirection
  if (e.deltaY > 0){
    scrollDirection = "down";
  } else if (e.deltaY < 0) {
    scrollDirection = "up";
  };
      
  scrollLogic();
  
});

// KeyStroke Support
$(window).keydown(function(e){
    
    if (e.keyCode == 38){
      scrollDirection = "up";
    } else if (e.keyCode == 40){
      scrollDirection = "down";
    } else if (e.keyCode == 39){
      scrollDirection = "down";
    } else if (e.keyCode = 37){
      scrollDirection = "up";
    } else {
      return;
    };
  
  scrollLogic();
  
});

// Swipe Support
$('#wrapper').swipe({
  swipe:function(event, direction, distance, duration, fingerCount){

    if (direction == "up"){
      scrollDirection = "down";
    } else if (direction == "down"){
      scrollDirection = "up";
    };

    scrollLogic();
    
  },
  threshold:100
});