scala-news-reader

jquery.keynav.js

(2055B)

 $.fn.keynav = (function () {
 	//a couple of global things for the plugin
 	var nodes = $(), positions = [], recalculate_positions, params;
 	params = {
 		keynext:  40,
 		keyprev:  38,
 		keynextJ: 74,
 		keyprevK: 75
 	};
 	//we're watching keypresses globally as well.
 	$(document).keydown(function(e) {
 		var st, prev, next, desired, i;
 		if (!nodes.length) {return true;}
 		if (e.target && e.target.tagName == 'TEXTAREA' || e.target.tagName == 'INPUT') {
 			return true;
 		}
 		if(e.keyCode == params.keynext || e.keyCode == params.keynextJ || e.keyCode == params.keyprevK || e.keyCode == params.keyprev) {
 			st = $(window).scrollTop();
 			//we're checking if our positions are still correct. it may not be necessary all the time, but just to be safe
 			if(positions[positions.length-1].top !== $(positions[positions.length-1].obj).offset().top) {
 				recalculate_positions();
 			}
 
 			if(e.keyCode === params.keynext || e.keyCode === params.keynextJ) {
 				for(i = positions.length-1; i > -1; i--) {
 					if(positions[i].top > st + 1) {desired = i;}
 				}
 			} else if(e.keyCode === params.keyprev || e.keyCode === params.keyprevK) {
 				for(i = 0; i < positions.length; i++) {
 					if(positions[i].top < st - 1) {desired = i;}
 				}
 			}
 
 			if(positions[desired]) {
 				$('html,body').animate({scrollTop: positions[desired].top}, 1);
 			} else {
 				$('html,body').animate({scrollTop: (e.keyCode === params.keynext || e.keyCode === params.keynextJ) ?
 				($('body').height() - $(window).height()) : 0}, 1);
 			}
 		}
 	});
 
 	recalculate_positions = function () {
 		//this recalculates the positions of nodes
 		var deduct = 0;
 		if($(window).width() > 979) { deduct = 50; }
 
 		positions = [];
 		nodes.each(function() {
 			positions.push({top: Math.floor($(this).offset().top - deduct),obj: this});
 		});
 	};
 
 	return function(newparams) {
 		//all we do in the actual plugin is we take the parameters and add the new nodes where we want to navigate.
 		params = $.extend(params,newparams || {});
 		nodes = nodes.add(this);
 		recalculate_positions();
 	};
 
 })();