Visit all Text nodes in Range (JavaScript)

VisitTextNodesInRange.js

//Range definition https://www.w3.org/TR/DOM-Level-2-Traversal-Range/ranges.html
function visitTextNodesInRange(range, visitor) {
  
  var reachedStartNode = false, reachedEndNode = false,
      startContainer = range.startContainer, endContainer = range.endContainer,
      startOffset = range.startOffset, endOffset = range.endOffset;
  
  var visitNode = function (node, visitor) {
    var isTextNode = node.nodeType === Node.TEXT_NODE;
    
    if (isTextNode) {
      if (node === startContainer && node === endContainer) {
        visitor(node, startOffset, endOffset);
      } else if (node === startContainer) {
        visitor(node, startOffset, node.nodeValue.length);
      } else if (node === endContainer) {
        visitor(node, 0, endOffset);
      } else if (reachedStartNode) {
        visitor(node, 0, node.nodeValue.length);
      }
    }

    var startIndex = node === startContainer && !isTextNode ? startOffset : 0;
    
    var endIndex = node === endContainer && !isTextNode ? endOffset : node.childNodes.length;
    
    reachedStartNode = reachedStartNode || node === startContainer;
    
    for (var i = startIndex; !reachedEndNode && i < endIndex; ++i) {
      visitNode(node.childNodes[i], visitor);
    }
    
    reachedEndNode = reachedEndNode || node === endContainer;
    
  };
  
  visitNode(range.commonAncestorContainer, visitor);
}

//Example usage: mask selected text with some placeholder
function maskSelectedText() {
  var visitor = function(textNode, startOffset, endOffset) {
    var value = textNode.nodeValue;
    var result = value.substring(0, startOffset);
    result += value.substring(startOffset, endOffset).replace(/[^\x00-\x7F]|\w/gim, '*');
    result += value.substring(endOffset);
    textNode.nodeValue = result;
  };
  
  if(window.getSelection && window.getSelection().rangeCount) {
    visitTextNodesInRange(window.getSelection().getRangeAt(0), visitor);
    window.getSelection().removeAllRanges();
  }
}