jquery.isinwindow.js

/*!
 * $.fn.isInWindow
 *
 * version 0.0.1 (2010/11/17)
 * author: Takeshi Takatsudo (takazudo[at]gmail.com)
 * license: MIT
 * depends: jQuery 1.4.4
 */
(function($, undefined){ // start encapsulation

	var $win = $(window);

	$.fn.isAboveTheWindow = function(opitons){
		var $el = this;
		if($el.size()>1){
			$.error('2 or more elements were thrown.');
			return false;
		}
		var o = $.extend({
			threshold: 0
		},opitons);
		return ($win.scrollTop() >= $el.offset().top + o.threshold  + $el.innerHeight());
	};
	$.fn.isBelowTheWindow = function(options){
		var $el = this;
		if($el.size()>1){
			$.error('2 or more elements were thrown.');
			return false;
		}
		var o = $.extend({
			threshold: 0
		},options);
		return $win.height() + $win.scrollTop() <= $el.offset().top - o.threshold;
	};
	$.fn.isInWindow = function(){
		var $el = this;
		return !$el.isAboveTheWindow() && !$el.isBelowTheWindow();
	};

})(jQuery); // end encapsulation