tablesorter/js/widgets/widget-cssStickyHeaders.js

/*! tablesorter CSS Sticky Headers widget - updated 2/9/2015 (v2.19.1)
* Requires a modern browser, tablesorter v2.8+
*/
/*jshint jquery:true, unused:false */
;(function($){
	'use strict';

	var ts = $.tablesorter;

	ts.addWidget({
		id: 'cssStickyHeaders',
		priority: 10,
		options: {
			cssStickyHeaders_offset        : 0,
			cssStickyHeaders_addCaption    : false,
			// jQuery selector or object to attach sticky header to
			cssStickyHeaders_attachTo      : null,
			cssStickyHeaders_filteredToTop : true
		},
		init : function(table, thisWidget, c, wo) {
			var ht, offst, adjustY,
				$table = c.$table,
				$attach = $(wo.cssStickyHeaders_attachTo),
				isIE = 'ActiveXObject' in window, // target all versions of IE
				namespace = c.namespace + 'cssstickyheader ',
				$thead = $table.children('thead'),
				$caption = $table.children('caption'),
				$win = $attach.length ? $attach : $(window),
				$parent = $table.parent().closest('table.' + ts.css.table),
				$parentThead = $parent.length && ts.hasWidget($parent[0], 'cssStickyHeaders') ? $parent.children('thead') : [],
				borderTopWidth = ( parseInt( $table.css('border-top-width'), 10 ) || 0 ),
				lastCaptionSetting = wo.cssStickyHeaders_addCaption,
				// table offset top changes while scrolling in FF
				adjustOffsetTop = false,
				addCaptionHeight = false,
				setTransform = function( $elms, y ) {
					var translate = y === 0 ? '' : 'translate(0px,' + y + 'px)';
					$elms.css({
						'transform' : translate,
						'-ms-transform' : translate,
						'-webkit-transform' : translate
					});
				};

			// Firefox fixes
			if ($caption.length) {
				// Firefox does not include the caption height when getting the table height
				// see https://bugzilla.mozilla.org/show_bug.cgi?id=820891, so lets detect it instead of browser sniff
				ht = $table.height();
				$caption.hide();
				addCaptionHeight = $table.height() === ht;
				$caption.show();

				// Firefox changes the offset().top when translating the table caption
				offst = $table.offset().top;
				setTransform( $caption, 20 );
				adjustOffsetTop = $table.offset().top !== offst;
				setTransform( $caption, 0 );
			}

			$win
			.unbind( $.trim('scroll resize '.split(' ').join(namespace)) )
			.bind( $.trim('scroll resize '.split(' ').join(namespace)), function() {
				// make sure "wo" is current otherwise changes to widgetOptions
				// are not dynamic (like the add caption button in the demo)
				wo = c.widgetOptions;

				if ( adjustOffsetTop ) {
					// remove transform from caption to get the correct offset().top value
					setTransform( $caption, 0 );
					adjustY = $table.offset().top;
				}

				var top = $attach.length ? $attach.offset().top : $win.scrollTop(),
				// add caption height; include table padding top & border-spacing or text may be above the fold (jQuery UI themes)
				// border-spacing needed in Firefox, but not webkit... not sure if I should account for that
				captionHeight = ( $caption.outerHeight(true) || 0 ) +
					( parseInt( $table.css('padding-top'), 10 ) || 0 ) +
					( parseInt( $table.css('border-spacing'), 10 ) || 0 ),

				bottom = $table.height() + ( addCaptionHeight && wo.cssStickyHeaders_addCaption ? captionHeight : 0 ) -
					$thead.height() - ( $table.children('tfoot').height() || 0 ) -
					( wo.cssStickyHeaders_addCaption ? captionHeight : ( addCaptionHeight ? 0 : captionHeight ) ),

				parentTheadHeight = $parentThead.length ? $parentThead.height() : 0,

				// get bottom of nested sticky headers
				nestedStickyBottom = $parentThead.length ? (
						isIE ? $parent.data('cssStickyHeaderBottom') + parentTheadHeight :
						$parentThead.offset().top + parentTheadHeight - $win.scrollTop()
					) : 0,

				// in this case FF's offsetTop changes while scrolling, so we get a saved offsetTop before scrolling occurs
				// but when the table is inside a wrapper ($attach) we need to continually update the offset top
				tableOffsetTop = adjustOffsetTop ? adjustY : $table.offset().top,

				offsetTop = addCaptionHeight ? tableOffsetTop - ( wo.cssStickyHeaders_addCaption ? captionHeight : 0 ) : tableOffsetTop,

				// Detect nested tables - fixes #724
				deltaY = top - offsetTop + nestedStickyBottom + borderTopWidth + ( wo.cssStickyHeaders_offset || 0 ) -
					( wo.cssStickyHeaders_addCaption ? ( addCaptionHeight ? captionHeight : 0 ) : captionHeight ),

				finalY = deltaY > 0 && deltaY <= bottom ? deltaY : 0,

				// All IE (even IE11) can only transform header cells - fixes #447 thanks to @gakreol!
				$cells = isIE ? $thead.children().children() : $thead;

				// more crazy IE stuff...
				if (isIE) {
					// I didn't bother testing 3 nested tables deep in IE, because I hate it
					c.$table.data( 'cssStickyHeaderBottom', ( $parentThead.length ? parentTheadHeight : 0 ) -
						( wo.cssStickyHeaders_addCaption ? captionHeight : 0 ) );
				}

				if (wo.cssStickyHeaders_addCaption) {
					$cells = $cells.add($caption);
				}
				if (lastCaptionSetting !== wo.cssStickyHeaders_addCaption) {
					lastCaptionSetting = wo.cssStickyHeaders_addCaption;
					// reset caption position if addCaption option is dynamically changed to false
					if (!lastCaptionSetting) {
						setTransform( $caption, 0 );
					}
				}

				setTransform( $cells, finalY );

			});
			$table.unbind( $.trim('filterEnd' + namespace) ).bind( $.trim('filterEnd' + namespace), function() {
				if (wo.cssStickyHeaders_filteredToTop) {
					// scroll top of table into view
					window.scrollTo(0, $table.position().top);
				}
			});

		},
		remove: function(table, c, wo, refreshing) {
			if (refreshing) { return; }
			var namespace = c.namespace + 'cssstickyheader ';
			$(window).unbind( $.trim('scroll resize '.split(' ').join(namespace)) );
			c.$table
				.unbind( $.trim('filterEnd scroll resize '.split(' ').join(namespace)) )
				.add( c.$table.children('thead').children().children() )
				.children('thead, caption').css({
					'transform' : '',
					'-ms-transform' : '',
					'-webkit-transform' : ''
				});
		}
	});

})(jQuery);