animhotep

function come(elem) {
	var docViewTop = $(window).scrollTop(),
		docViewBottom = docViewTop + $(window).height(),
		elemTop = $(elem).offset().top,
		elemBottom = elemTop + $(elem).height();

	return ((elemBottom <= docViewBottom) && (elemTop >= docViewTop));
}

if (come("#section2")) {
    ...
}