/**
 * File skip-link-focus-fix.js.
 *
 * Helps with accessibility for keyboard only users.
 *
 * Learn more: https://git.io/vWdr2
 */
(function () {
	var isIe = /(trident|msie)/i.test( navigator.userAgent );

	if (isIe && document.getElementById && window.addEventListener) {
		window.addEventListener(
			'hashchange',
			function () {
				var id = location.hash.substring( 1 ),
					element;

				if ( ! (/^[A-z0-9_-]+$/.test( id ))) {
					return;
				}

				element = document.getElementById( id );

				if (element) {
					if ( ! (/^(?:a|select|input|button|textarea)$/i.test( element.tagName ))) {
						element.tabIndex = -1;
					}

					element.focus();
				}
			},
			false
		);
	}
})();