2SHANEZ

background.js

(function () {
  const ELEMENT_NODE = 1;
  const TEXT_NODE = 3;
  // https://stackoverflow.com/a/34559316

  function walkText(node) {
    if (node.nodeType == TEXT_NODE) {
      node.data = node.data.replace(/(?<=[ \t]|(?:^|\"|\-|\=|(?:[.!?]\s)))(Sean|sean)(?=([ \t]|\.|\'||\-|\=|\"|\?|\/|\,))/g, "Shane");
    } else if (node.nodeType == ELEMENT_NODE && node.nodeName != "SCRIPT") {
      for (var i = 0; i < node.childNodes.length; i++) {
        walkText(node.childNodes[i]);
      }
    }
  }
  walkText(document.body);

  document.title = document.title.replace(/(?<=[ \t]|(?:^|\"|\-|\=|(?:[.!?]\s)))(Sean|sean)(?=([ \t]|\.|\'||\-|\=|\"|\?|\/|\,))/g, "Shane");
})();

manifest.json

  {
    "name": "2Shanez",
    "version": "1.0",
    "description": "Sean 2 Shane",
    "manifest_version": 2,
    "persistent": false,
    "content_scripts": [
      {
        "matches": [
          "<all_urls>"
        ],
        "js": [
          "background.js"
        ],
        "run_at": "document_end"
      }
    ]
  }