JSFiddle - React, Tailwind, and code Playground

by ramsesoriginal

HTML

<a href="a">A</a>
<a href="b">B</a>
<a href="a">A</a>
<a href="c">C</a>

CSS

a:before
{
content:attr(data-counter)". ";
}

JavaScript

var linkcounter = {};
var counter = 0;

var anchors = document.getElementsByTagName('a');
for(var i = 0; i < anchors.length; i++) {
    if (!linkcounter.hasOwnProperty(anchors[i].getAttribute("href"))) {
        counter++;
        linkcounter[anchors[i].getAttribute("href")] = counter;
    }
    anchors[i].setAttribute("data-counter", linkcounter[anchors[i].getAttribute("href")]);
}
alert(counter);