Autoplay Text Slider by using HTML, CSS & JavaScript

<div class="slideshow-container">

  <div class="mySlides">
    <q>I love you the more in that I believe you had liked me for my own sake and for nothing else</q>
    <p class="author">- John Keats</p>
  </div>

  <div class="mySlides">
    <q>But man is not made for defeat. A man can be destroyed but not defeated.</q>
    <p class="author">- Ernest Hemingway</p>
  </div>

  <div class="mySlides">
    <q>I have not failed. I've just found 10,000 ways that won't work.</q>
    <p class="author">- Thomas A. Edison</p>
  </div>

  <a class="prev" onclick="plusSlides(-1)">❮</a>
  <a class="next" onclick="plusSlides(1)">❯</a>

</div>

<div class="dot-container">
  <span class="dot" onclick="currentSlide(1)"></span> 
  <span class="dot" onclick="currentSlide(2)"></span> 
  <span class="dot" onclick="currentSlide(3)"></span> 
</div>

/* Slideshow container */
.slideshow-container {
  position: relative;
  background: #f1f1f1f1;
}

/* Slides */
.mySlides {
  display: none;
  padding: 80px;
  text-align: center;
}

/* Next & previous buttons */
.prev, .next {
  cursor: pointer;
  position: absolute;
  top: 50%;
  width: auto;
  margin-top: -30px;
  padding: 16px;
  color: #888;
  font-weight: bold;
  font-size: 20px;
  border-radius: 0 3px 3px 0;
  user-select: none;
}

/* Position the "next button" to the right */
.next {
  position: absolute;
  right: 0;
  border-radius: 3px 0 0 3px;
}

/* On hover, add a black background color with a little bit see-through */
.prev:hover, .next:hover {
  background-color: rgba(0,0,0,0.8);
  color: white;
}

/* The dot/bullet/indicator container */
.dot-container {
    text-align: center;
    padding: 20px;
    background: #ddd;
}

/* The dots/bullets/indicators */
.dot {
  cursor: pointer;
  height: 15px;
  width: 15px;
  margin: 0 2px;
  background-color: #bbb;
  border-radius: 50%;
  display: inline-block;
  transition: background-color 0.6s ease;
}

/* Add a background color to the active dot/circle */
.active, .dot:hover {
  background-color: #717171;
}

/* Add an italic font style to all quotes */
q {font-style: italic;}

/* Add a blue color to the author */
.author {color: cornflowerblue;}

var slideIndex = 1;
showSlides(slideIndex);

function plusSlides(n) {
  showSlides(slideIndex += n);
}

function currentSlide(n) {
  showSlides(slideIndex = n);
}

function showSlides(n) {
  var i;
  var slides = document.getElementsByClassName("mySlides");
  var dots = document.getElementsByClassName("dot");
  if (n > slides.length) {slideIndex = 1}    
  if (n < 1) {slideIndex = slides.length}
  for (i = 0; i < slides.length; i++) {
      slides[i].style.display = "none";  
  }
  for (i = 0; i < dots.length; i++) {
      dots[i].className = dots[i].className.replace(" active", "");
  }
  slides[slideIndex-1].style.display = "block";  
  dots[slideIndex-1].className += " active";
}

window.onload= function () {
  setInterval(function(){ 
     plusSlides(1);
  }, 3000);
 }