Get offset position of text in JavaScript

text-offset.js

var characters = document.querySelector('.characters'); // div with text
var charactersText = characters.textContent;
var charAtIndex = 25;
var offsetPosition;

characters.textContent = '';
for (var i = 0; i < charactersText.length; i++) {
    var textNode = document.createTextNode(charactersText[i]);
    characters.appendChild(textNode);
    if (i === charAtIndex) {
        var range = document.createRange();
        range.selectNodeContents(textNode);
        var rects = range.getClientRects();
        offsetPosition = {
            left: rects[0].left,
            top: rects[0].top
        };
    }
}

alert(JSON.stringify(offsetPosition, null, 2));

https://github.com/miguelmota/textnode-offset ;)