src/core/utils/covervid.js

export default function coverVid(elem, width, height) {

	// debounce for resize function
	function debounce(fn, delay) {
		let timer = null;

		return function () {
			let context = this,
				args = arguments;

			window.clearTimeout(timer);

			timer = window.setTimeout(function () {
				fn.apply(context, args);
			}, delay);
		};
	}

	// Set necessary styles to position video "center center"
	elem.style.position = "absolute";
	elem.style.top = "50%";
	elem.style.left = "50%";
	elem.style["-webkit-transform"] = "translate(-50%, -50%)";
	elem.style["-ms-transform"] = "translate(-50%, -50%)";
	elem.style.transform = "translate(-50%, -50%)";

	// Set overflow hidden on parent element
	elem.parentNode.style.overflow = "hidden";

	// Get image defined on poster attribute of video
	let posterImage = elem.getAttribute("poster");

	// Remove poster to disable
	elem.removeAttribute("poster");

	// Set poster image as a background cover image on parent element
	elem.parentNode.style.backgroundImage = "url(" + posterImage + ")";
	elem.parentNode.style.backgroundSize = "cover";
	elem.parentNode.style.backgroundPosition = "center center";

	// Define the attached selector
	function sizeVideo() {

		// Get parent element height and width
		let parentHeight = elem.parentNode.offsetHeight;
		let parentWidth = elem.parentNode.offsetWidth;

		// Get native video width and height
		let nativeWidth = width;
		let nativeHeight = height;

		// Get the scale factors
		let heightScaleFactor = parentHeight / nativeHeight;
		let widthScaleFactor = parentWidth / nativeWidth;

		// Based on highest scale factor set width and height
		if (widthScaleFactor > heightScaleFactor) {
			elem.style.height = "auto";
			elem.style.width = parentWidth+"px";
		} else {
			elem.style.height = parentHeight+"px";
			elem.style.width = "auto";
		}
	}

	// Check for video support
	let supportsVideo = (typeof(elem.canPlayType) != "undefined") ? true : false;

	// Check if mobile
	let isMobile = false;
	if(/(android|bb\d+|meego).+mobile|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|iris|kindle|Android|Silk|lge |maemo|midp|mmp|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows (ce|phone)|xda|xiino/i.test(navigator.userAgent)
  	|| /1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s\-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|\-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw\-(n|u)|c55\/|capi|ccwa|cdm\-|cell|chtm|cldc|cmd\-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc\-s|devi|dica|dmob|do(c|p)o|ds(12|\-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly(\-|_)|g1 u|g560|gene|gf\-5|g\-mo|go(\.w|od)|gr(ad|un)|haie|hcit|hd\-(m|p|t)|hei\-|hi(pt|ta)|hp( i|ip)|hs\-c|ht(c(\-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i\-(20|go|ma)|i230|iac( |\-|\/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |\/)|klon|kpt |kwc\-|kyo(c|k)|le(no|xi)|lg( g|\/(k|l|u)|50|54|\-[a-w])|libw|lynx|m1\-w|m3ga|m50\/|ma(te|ui|xo)|mc(01|21|ca)|m\-cr|me(rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t(\-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)\-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|\-([1-8]|c))|phil|pire|pl(ay|uc)|pn\-2|po(ck|rt|se)|prox|psio|pt\-g|qa\-a|qc(07|12|21|32|60|\-[2-7]|i\-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55\/|sa(ge|ma|mm|ms|ny|va)|sc(01|h\-|oo|p\-)|sdk\/|se(c(\-|0|1)|47|mc|nd|ri)|sgh\-|shar|sie(\-|m)|sk\-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h\-|v\-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl\-|tdg\-|tel(i|m)|tim\-|t\-mo|to(pl|sh)|ts(70|m\-|m3|m5)|tx\-9|up(\.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|\-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c(\-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas\-|your|zeto|zte\-/i.test(navigator.userAgent.substr(0,4)))
		isMobile = true;
	
	// call sizeVideo on load
	sizeVideo();	
	
	// Remove video if not supported or mobile
	if (!supportsVideo || isMobile) {
		elem && elem.parentNode && elem.parentNode.removeChild(elem);
	}

	// call sizeVideo on resize
	window.addEventListener("resize", debounce(sizeVideo, 50));
};