JSFiddle - React, Tailwind, and code Playground
by Turi S
HTML
<p id="targetElement">There is a long sentence here.
The sentence is so long that it overflows from the element.</p>
CSS
#targetElement{
width:100px;
height:50px;
overflow-y:auto;
position: relative;
}
JavaScript
var $elem = $('#targetElement');
alert(nthCharOffset($elem, 21));
function nthCharOffset($elem, charIndex) {
var text = $elem.html();
var pattern = new RegExp("^(.{"+charIndex+"})(.)");
var newText = text.replace(pattern, '$1<span class="get-position-of-it">$2</span>');
$elem.html(newText); //Set wrapper
var offset = $(".get-position-of-it").position();
$elem.html(text); //Place back
return offset.top;
}