Edit in JSFiddle

let GrammarChecker = window["BeyondGrammar"]["GrammarChecker"];
let editor = document.getElementById("contenteditable-editor");

let settings = {
  service: {

    //You should signup for getting this key
    apiKey: "E8FEF7AE-3F36-4EAF-A451-456D05E6F2A3",

    //[optional] You can specify it for permanent access to your settings and dictionaries
    //userId: "<YOUR_USER_ID>",

    //[optional] path to js file with BeyondGrammar Core
    //sourcePath : "", 

    //[optional] path to service which provides grammar checking
    // url shouldn't contain "/" in the end
    serviceUrl: "https://rtg.prowritingaid.com",
  },
  grammar: {
    languageFilter: ["en-US", "en-GB"],

    //[optional] Default language [en-US, en-GB],
    languageIsoCode: "en-US",

    //[optional] checking Style. By default is "true"
    checkStyle: true,

    //[optional] checking Spelling. By default is "true"
    checkSpelling: true,

    //[optional] checking Grammar. By default is "true"
    checkGrammar: true,

    //[optional] Show thesaurus information by double click, by default true
    showThesaurusByDoubleClick: true,

    //[optional] Showing context thesaurus, works only if showThesaurusByDoubleClick = true, by default false
    showContextThesaurus: false,
  }
}

let checker = new GrammarChecker(editor, settings.service, settings.grammar);

checker.init()
  .then(() => {
    //grammar checker is inited and can be activate
    checker.activate()
  })

<script src="//cdn.prowritingaid.com/beyondgrammar/2.0.2893/dist/hayt/bundle.js"></script>
<div contenteditable="" spellcheck="false" id="contenteditable-editor">
  <p>
    Novalk Djokovic is set to miss the US Open after one of his doctors made an announcement that he will need six to twelve weeks to recovers from a elbow injury.
  </p>

  <p>
    But Andy Murrey's chances of playing at Flushing Meadows would appear more positive, with the Scot continuing his rehabilitation from a hip problem.
  </p>

  <p>
    The last grandslam of the year starts in just under five weeks on August 28, meaning Djokovic will run out of time if the latest assessment is correct.
  </p>

  <p>
    <b>Injured Djokovic starting to consider a break away from tennis</b>
    <br>The 12-time major champion was forced to retire injured during his Wimbeldon quarter-final against Tomas Berdych earlier this month and said after the match that he had been feeling pain in his right elbow for over a year and a half. According to
    his physio its not doing very well. If he does return he will be more likely to injure it again.
  </p>

  <p>
    He has since been seeking advice from specialists, including Serbian doctor Zdenko Milinkovic, who said Djokovic is suffering from a "bruised bone due to excessive playing".
  </p>

  <p>"Nole must rest for six to 12 weeks," Milinkovic told Sportski Zurnal, a sports newspaper in Serbia.</p>

  <p>
    The next examination will know wether this asdsessment stays or changes. During this period, he is not going to train with a racket but he will run other sessions, such as fitness and the like.
  </p>
</div>

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