Function inject

src/injected/content/inject.js:269–332

(item, iframeCb)

}

function inject(item, iframeCb) {
  const { code } = item;
  const isCodeArray = isObject(code);
  const script = makeElem('script', !isCodeArray && code);
  // Firefox ignores sourceURL comment when a syntax error occurs so we'll print the name manually
  const onError = IS_FIREFOX && !iframeCb && (e => {
    const { stack } = e[ERROR];
    if (!stack || `${stack}`.includes(VM_UUID)) {
      log(ERROR, [item.displayName + ':' + e.lineno + ':' + e.colno], e[ERROR]);
      e.preventDefault();
    }
  });
  const div = makeElem('div');
  // Hiding the script's code from mutation events like DOMNodeInserted or DOMNodeRemoved
  const divRoot = injectedRoot || (
    attachShadow
      ? div::attachShadow({ mode: 'closed' })
      : div
  );
  if (isCodeArray) {
    safeApply(append, script, code);
  }
  addNonceAttribute(script);
  let iframe;
  let iframeDoc;
  if (iframeCb) {
    iframe = makeElem('iframe', {
      /* Preventing other content scripts */// eslint-disable-next-line no-script-url
      src: 'javascript:void 0',
      sandbox: 'allow-same-origin allow-scripts',
      style: 'display:none!important',
    });
    /* In FF the opener receives DOMNodeInserted attached at creation so it can see window[0] */
    if (!IS_FIREFOX) {
      divRoot::appendChild(iframe);
    }
  } else {
    divRoot::appendChild(script);
  }
  if (onError) {
    window::on(ERROR, onError);
  }
  if (!injectedRoot) {
    // When using declarativeContent there's no documentElement so we'll append to `document`
    (elemByTag('*') || document)::appendChild(div);
  }
  if (onError) {
    window::off(ERROR, onError);
  }
  if (iframeCb) {
    injectedRoot = divRoot;
    if (IS_FIREFOX) divRoot::appendChild(iframe);
    // Can be removed in DOMNodeInserted by a hostile web page or CSP forbids iframes(?)
    if ((iframeDoc = iframe.contentDocument)) {
      iframeDoc::getElementsByTagName('*')[0]::appendChild(script);
      iframeCb();
    }
    iframe::remove();