selectText.js

  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, this.getTextNodesIn(children[i]));
        }
    }
    return textNodes;
  }

  setSelectionRange = (el, start, end) => {
    if (document.createRange && window.getSelection) {
        var range = document.createRange();
        range.selectNodeContents(el);
        var textNodes = this.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 = document.body.createTextRange();
        textRange.moveToElementText(el);
        textRange.collapse(true);
        textRange.moveEnd("character", end);
        textRange.moveStart("character", start);
        textRange.select();
    }
  }

Hi,
can you share some logic to get all child nodes and creating range of highlight text on web ?
scenario: when user select some text and do highlight on web , I want to validate that text range and elment rect
objHighlightOverlay.clientWidth and rangItem.width