/**
 * 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
			);
		}
	}
)();