Detect Scroll direction

scroll-direction.js

//INSTANCE
var scroller = new scrollDirection({
	minHeight: 200,
	step: 32,
	orientation: 'vertical',
	scrollUp: function() { $( '.navbar-fixed-top' ).addClass( 'collapsed' ) },
	scrollDown: function() { $( '.navbar-fixed-top' ).removeClass( 'collapsed' ) },
});

//INIT
scroller.init();

//FUNCTION
function scrollDirection ( option ) {
	var option = option || {};
	this.posNew = 0;
	this.posOld = 0;
	this.direction = null;
	this.point = 0;
	this.distance = 0;
	this.status = null;

	// container scroll
	this.$scroller = option.scroller || $( window );
	// Orientation of scroll
	this.orientation = option.orientation || 'vertical';
	// Number of pixel scrolled to trigger a function
	this.step = option.step || 10;
	// height min before enable stepsensor()
	this.minHeight = option.minHeight || 0;

	// Event on scroll
	this.eventScroll = option.scroll || function (){ return false };
	// Event on scroll UP
	this.eventScrollUp = option.scrollUp || function (){ return false };
	// Event on scroll DOWN
	this.eventScrollDown = option.scrollDown || function (){ return false };

	// Get scroll top
	this.getScrollPos = function (){
		if ( this.orientation == 'vertical' ) return this.$scroller.scrollTop();
		if ( this.orientation == 'horizontal' ) return this.$scroller.scrollLeft();
	}

	// Detect direction of scroll
	this.directionSensor = function (){
		this.posNew = this.getScrollPos();
		console.log(this.posNew);
		if ( this.posNew > this.posOld && this.posNew > this.minHeight ) this.stepSensor( false ); ;
		if ( this.posNew < this.posOld && this.posNew > this.minHeight ) this.stepSensor( true ); ;
		this.posOld = this.posNew;
	};

	// calcul distance scrolled and trigger a function
	this.stepSensor = function ( bool ) {

		console.log('stepSensor enable');

		if ( bool != this.status ){
			this.point = this.getScrollPos();
			this.distance = 0;
		}

		this.distance = this.point - this.getScrollPos();

		if ( this.distance > this.step ) this.eventScrollDown();
		if ( this.distance < - this.step ) this.eventScrollUp();

		this.status = bool;

		this.eventScroll();
	};

	//init plugin
	this.init = function () {
		var that = this;
		this.$scroller.on( 'scroll', function () { that.directionSensor() });
	};
}