isElementInViewport

iselementinviewport.js

	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)
		);
	}