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JavaScript

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HTML 

              
                <h1>Random Ron Without Duplicates</h1>

<p>
  <img src="https://www.incimages.com/uploaded_files/image/1920x1080/parks-and-recreation_32716.jpg" alt="Ron Swanson, from the American sitcom 'Parks and Recreation', portrayed by Nick Offerman.">
</p>

<blockquote>
  <p id="quote" aria-live="polite">One moment while I find a quote...</p>
</blockquote>

<p>
  <button id="new-quote" type="button">More Ron</button>
</p>
!

CSS 

              
                body {
  display: flex;
  flex-direction: column;
  justify-content: center;
  max-width: 30rem;
  padding: 1rem;
  margin: 0 auto;
  font-family: Georgia, serif;
  color: #222;
}

body > * + * {
  margin-top: 1rem;
}

h1 {
  color: #444;
}

h1::before {
  content: '💬 ';
}

blockquote {
  font-size: 1.5rem;
}

blockquote p::before {
  content: open-quote;
}

blockquote p::after {
  content: close-quote;
}

button {
  font-size: 1.25rem;
  font-family: Arial, sans-serif;
}
!

JS 

              
                //
// Variables
//

// Get the placeholder for the quote
const placeholder = document.querySelector('#quote');

// Get the button for fetching new quotes
const button = document.querySelector('#new-quote');

// Store the API endpoint
const endpoint = 'https://ron-swanson-quotes.herokuapp.com/v2/quotes';

// Store the last 50 quotes
const pastQuotes = [];


//
// Functions
//

/**
 * Get the JSON data from a Fetch request
 * @param {Response} response The Response object
 * @returns {Promise} The JSON data or the rejected response
 */
function getJSON (response) {
  return response.ok ? response.json() : Promise.reject(response);
}

/**
 * Make sure the quote is valid and get a new one if necessary
 * @param {String[]} quotes An array of quotes
 * @returns {String} A quote
 */
function checkQuote (quotes) {
  // Get a new quote if necessary
  if (pastQuotes.includes(quotes[0])) {
    return fetch(endpoint).then(getJSON).then(checkQuote);
  }

  // Limit the past quotes to 50 quotes
  if (pastQuotes.length === 50) {
    pastQuotes.shift();
  }

  // Add this quote to the past quotes
  pastQuotes.push(quotes[0]);

  // Return the quote
  return quotes[0];
}

/**
 * Add a quote to the DOM
 * @param {String} quote The quote to be added
 */
function showQuote (quote) {
  placeholder.textContent = quote;
}

/**
 * Add an error message to the DOM
 */
function showError () {
  placeholder.textContent = 'I tried to find a quote, but something went wrong. Come back later, and be ready. Because I am. I was born ready. I\'m Ron F*cking Swanson.';
}

/**
 * Fetch a quote and add it to the DOM
 */
function fetchQuote () {
  fetch(endpoint)
    .then(getJSON)
    .then(checkQuote)
    .then(showQuote)
    .catch(showError);
}


//
// Inits & Event Listeners
//

// Show a quote when the page loads
fetchQuote();

// Show a new quote when the button is clicked
button.addEventListener('click', fetchQuote);
!
999px

Console