Chạy script khi scroll đến element

$(allInView);
$(window).scroll(allInView);
function isScrolledIntoView(elem) {
    var docViewTop = $(window).scrollTop();
    var docViewBottom = docViewTop + $(window).height();
    var elemTop = $(elem).offset().top;
    var elemBottom = elemTop + $(elem).height();	
    return ((elemBottom <= docViewBottom) && (elemTop >= docViewTop));
}
var inited = false;
function allInView() {	
	if (inited) {
    return
	}
    if (isScrolledIntoView($(".postads"))){
		alert('hù');
		inited = true;
		init();
	}
};