All Your Base ...

Override base href URL with window location to restore hash navs.

by Rynne Cowham

HTML

<base href="//www.pacific.edu">

<a href="#tab-1">Example.com</a>
<br>
<a href="#tab-2">Google.com</a>
<br>
<a href="#tab-3">Wikipedia.org</a>

JavaScript

var anchors = document.querySelectorAll("a[href*='#']");
Array.prototype.forEach.call(anchors, function (element, index) {
    element.href = window.location.href + "#tab-" + (index + 1);
});