JSFiddle - React, Tailwind, and code Playground

HTML

<a href="http://google.com">Hello, world!</a><br />
<a href="http://yahoo.com">Hello, world!</a><br />
<a href="http://facebook.com">Hello, world!</a><br />
<a href="http://globe.com">Hello, world!</a><br />
<input type="button" id="change" value="Change HREF" />

JavaScript

$('#change').click(function(){
    var newData = '#okok'; // fake new data
    $('a').each(function(i,e){
        var oldHref = $(this).data('oldHref');
        if (!oldHref){
            var oldHref = $(this).attr('href');
            $(this).data('oldHref',oldHref);
        }
        $(this).attr('href',oldHref + '#' + newData);
    });
});