JSFiddle - React, Tailwind, and code Playground

HTML

<script>
        function getCursorPos(el) {
        var val = el.value;
        document.getElementById("CursorPos").innerHTML=val.slice(0, el.selectionStart).length;
    }
    </script>
    <input type=text id="t1" value="abcd" onclick="getCursorPos(this);">
    <div id="CursorPos"></div>