WDS Javascript Back To Top

wds-back-to-top.js

/**
 * Back To Top.
 */
window.Back_To_Top = {};
( function( window, $, that ) {

	// Private variables.
	var minWidth = 768;
	var minHeight = 200;

	// Constructor.
	that.init = function() {
		that.cache();

		if ( that.meetsRequirements ) {
			that.bindEvents();
		}
	};

	// Cache all the things.
	that.cache = function() {
		that.$c = {
			window: $( window ),
			backToTopWrap: $( '.btt-area' ),
			htmlBody: $( 'html, body' ),
		};
	};

	// Combine all events.
	that.bindEvents = function() {
		that.$c.window.on( 'scroll',  that.displayBackToTop );
		that.$c.backToTopWrap.on( 'click', that.animateScroll );
	};

	// Do we meet the requirements?
	that.meetsRequirements = function() {
		return that.$c.backToTopWrap.length && minWidth <= that.$c.window.width();
	};

	// Fade the Back To Top link.
	that.displayBackToTop = function() {
		// If we've scrolled down at least 200 pixels, fade in.
		if ( that.$c.window.scrollTop() > minHeight ) {
			that.$c.backToTopWrap.fadeIn( minHeight );

		// Otherwise, fade out.
		} else {
			that.$c.backToTopWrap.fadeOut( minHeight );
		}
	};

	// Animate the scroll back up.
	that.animateScroll = function(e) {
		e.preventDefault();
		that.$c.htmlBody.animate({scrollTop: 0}, 300);
	};

	// Engage!
	$( that.init );

})( window, jQuery, window.Back_To_Top );