118 lines
3.4 KiB
JavaScript
118 lines
3.4 KiB
JavaScript
/* jSticky Plugin
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* =============
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* Author: Andrew Henderson (@AndrewHenderson)
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* Contributor: Mike Street (@mikestreety)
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* Date: 9/7/2012
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* Update: 09/20/2016
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* Website: http://github.com/andrewhenderson/jsticky/
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* Description: A jQuery plugin that keeps select DOM
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* element(s) in view while scrolling the page.
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*/
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;(function($) {
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$.fn.sticky = function(options) {
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var defaults = {
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topSpacing: 0, // No spacing by default
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zIndex: '', // No default z-index
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stopper: '.sticky-stopper', // Default stopper class, also accepts number value
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stickyClass: false // Class applied to element when it's stuck
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};
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var settings = $.extend({}, defaults, options); // Accepts custom stopper id or class
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// Checks if custom z-index was defined
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function checkIndex() {
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if (typeof settings.zIndex == 'number') {
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return true;
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} else {
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return false;
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}
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}
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var hasIndex = checkIndex(); // True or false
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// Checks if a stopper exists in the DOM or number defined
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function checkStopper() {
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if (0 < $(settings.stopper).length || typeof settings.stopper === 'number') {
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return true;
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} else {
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return false;
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}
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}
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var hasStopper = checkStopper(); // True or false
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return this.each(function() {
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var $this = $(this);
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var thisHeight = $this.outerHeight();
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var thisWidth = $this.outerWidth();
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var topSpacing = settings.topSpacing;
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var zIndex = settings.zIndex;
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var pushPoint = $this.offset().top - topSpacing; // Point at which the sticky element starts pushing
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var placeholder = $('<div></div>').width(thisWidth).height(thisHeight).addClass('sticky-placeholder'); // Cache a clone sticky element
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var stopper = settings.stopper;
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var $window = $(window);
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function stickyScroll() {
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var windowTop = $window.scrollTop(); // Check window's scroll position
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var stopPoint = stopper;
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var parentWidth = $this.parent().width();
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placeholder.width(parentWidth)
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if ( hasStopper && typeof stopper === 'string' ) {
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var stopperTop = $(stopper).offset().top;
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stopPoint = (stopperTop - thisHeight) - topSpacing;
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}
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if (pushPoint < windowTop) {
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// Create a placeholder for sticky element to occupy vertical real estate
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if(settings.stickyClass)
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$this.addClass(settings.stickyClass);
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$this.after(placeholder).css({
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position: 'fixed',
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top: topSpacing,
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width: parentWidth
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});
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if (hasIndex) {
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$this.css({
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zIndex: zIndex
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});
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}
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if (hasStopper) {
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if (stopPoint < windowTop) {
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var diff = (stopPoint - windowTop) + topSpacing;
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$this.css({
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top: diff
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});
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}
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}
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} else {
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if(settings.stickyClass)
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$this.removeClass(settings.stickyClass);
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$this.css({
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position: 'static',
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top: null,
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left: null,
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width: 'auto'
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});
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placeholder.remove();
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}
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}
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if($window.innerHeight() > thisHeight) {
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$window.bind('scroll', stickyScroll);
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$window.bind('load', stickyScroll);
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$window.bind('resize', stickyScroll);
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}
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});
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};
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})(jQuery);
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