jQuery. check if element in viewport

check-element-in-viewport.js

$.fn.inViewport = function(){
	var win = $(window);
	var self = $(this);
	var posOnPage = win.scrollTop();
	var selfOffset = self.offset().top;
	var visiblePartOfpage =  posOnPage + win.height();
	var endOfElPos = selfOffset + self.outerHeight();
	return (visiblePartOfpage >= selfOffset && visiblePartOfpage <= endOfElPos ? true : false);
}

$(window).scroll(function(){
	console.log($("id").inViewport());
})