JSFiddle - React, Tailwind, and code Playground

by Daniel DeGroff

HTML

<div id="zone">
    <span>Hello </span><strong>world</strong>!
</div>

JavaScript

function selectText(element, textToSelect) {
    var elementText;
    if (typeof element.textContent == "string" && document.createRange && window.getSelection) {
        elementText = element.textContent;
    } else if (document.selection && document.body.createTextRange) {
        var textRange = document.body.createTextRange();
        textRange.moveToElement(element);
        elementText = textRange.text;
    }
    
    var startIndex = elementText.indexOf(textToSelect);
    setSelectionRange(element, startIndex, startIndex + textToSelect.length);
}

function getTextNodesIn(node) {
    var textNodes = [];
    if (node.nodeType == 3) {
        textNodes.push(node);
    } else {
        var children = node.childNodes;
        for (var i = 0, len = children.length; i < len; ++i) {
            textNodes.push.apply(textNodes, getTextNodesIn(children[i]));
        }
    }
    return textNodes;
}

function setSelectionRange(el, start, end) {
    if (document.createRange && window.getSelection) {
        var range = document.createRange();
        range.selectNodeContents(el);
        var textNodes = getTextNodesIn(el);
        var foundStart = false;
        var charCount = 0, endCharCount;

        for (var i = 0, textNode; textNode = textNodes[i++]; ) {
            endCharCount = charCount + textNode.length;
            if (!foundStart && start >= charCount
                    && (start < endCharCount ||
                    (start == endCharCount && i < textNodes.length))) {
                range.setStart(textNode, start - charCount);
                foundStart = true;
            }
            if (foundStart && end <= endCharCount) {
                range.setEnd(textNode, end - charCount);
                break;
            }
            charCount = endCharCount;
        }

        var sel = window.getSelection();
        sel.removeAllRanges();
        sel.addRange(range);
    } else if (document.selection && document.body.createTextRange) {
        var textRange...