var animate_scroll_listener;
function begin_scroll_checker() {
	animate_scroll_listener = scroll_check();
	window.addEventListener('scroll', animate_scroll_listener);
}
begin_scroll_checker();
var watch_elements = $('.watch-scroll');
var scrolled_elements = 0;
function scroll_check() {
	return function scroll_event() {
		watch_elements.each(function(){
			if( $(this).hasClass('animate') ) return;
			if( isElementInViewport(this) ) {
				// Element is in viewport, click
				$(this).addClass('animate');
				scrolled_elements++;
			}
		});
		if( scrolled_elements >= watch_elements.length ) {
			// no more elements, remove scroll event
			window.removeEventListener('scroll', animate_scroll_listener);
		}
	}
}
function isElementInViewport(el) {
	if ( document.documentElement.clientWidth <= 767 && document.documentElement.clientHeight < document.documentElement.clientWidth ) {
		return $(el).is(':visible');
	}

	if (typeof jQuery === "function" && el instanceof jQuery) {
		el = el[0];
	}

	var rect = el.getBoundingClientRect();

	return (
		rect.top >= 0 &&
		rect.left >= 0 &&
		rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) &&
		rect.right <= (window.innerWidth || document.documentElement.clientWidth)
	);
}