Waits for Element to exist on the DOM

element-ready.js

 /**
 * Waits for an element satisfying selector to exist, then resolves promise with the element.
 * Useful for resolving race conditions.
 *
 * @param selector
 * @returns {Promise}
 */
function elementReady(selector) {
    return new Promise((resolve, reject) => {
      let el = document.querySelector(selector);
      if (el) {resolve(el);}
      new MutationObserver((mutationRecords, observer) => {
        // Query for elements matching the specified selector
        Array.from(document.querySelectorAll(selector)).forEach((element) => {
          resolve(element);
          //Once we have resolved we don't need the observer anymore.
          observer.disconnect();
        });
      })
        .observe(document.documentElement, {
          childList: true,
          subtree: true
        });
    });
  }



  elementReady('#_ghostery-title').then( (target) => {
    target.focus()
  });