https://www.whymarche.com/wp-content/themes/melina/assets/js/skip-link-focus-fix.js?ver=20151215

1/**
2 * File skip-link-focus-fix.js.
3 *
4 * Helps with accessibility for keyboard only users.
5 *
6 * Learn more: https://git.io/vWdr2
7 */
8
9( function() {
10	"use strict";
11
12	var isIe = /(trident|msie)/i.test( navigator.userAgent );
13
14	if ( isIe && document.getElementById && window.addEventListener ) {
15		window.addEventListener( 'hashchange', function() {
16			var id = location.hash.substring( 1 ),
17				element;
18
19			if ( ! ( /^[A-z0-9_-]+$/.test( id ) ) ) {
20				return;
21			}
22
23			element = document.getElementById( id );
24
25			if ( element ) {
26				if ( ! ( /^(?:a|select|input|button|textarea)$/i.test( element.tagName ) ) ) {
27					element.tabIndex = -1;
28				}
29
30				element.focus();
31			}
32		}, false );
33	}
34} )();