Simple Responsive Slideshow With CSS JS (Free Download)

Welcome to a tutorial on how to create a simple responsive slideshow with pure CSS and vanilla Javascript. Yes, there are a lot of crazy slideshow plugins on the Internet. But some of them require the use of third-party libraries, which adds to the undesired loading bloat – So here it is, a simple and lightweight slideshow that you can use. Read on!

ⓘ I have included a zip file with all the source code at the start of this tutorial, so you don’t have to copy-paste everything… Or if you just want to dive straight in.

 

TABLE OF CONTENTS

 

 

 

QUICK NOTES

If you spot a bug, feel free to comment below. I try to answer short questions too, but it is one person versus the entire world… If you need answers urgently, please check out my list of websites to get help with programming.

 

SOURCE CODE DOWNLOAD

Click here to download the source code, I have released it under the MIT license, so feel free to build on top of it or use it in your own project.

 

HOW TO USE & DEMO

<!-- (A) LOAD LIBRARY -->
<link rel="stylesheet" href="slides.css">
<script defer src="slides.js"></script>

<!-- (B) EMPTY HTML DIV -->
<div id="demo"></div>

<!-- (C) ATTACH SLIDESHOW -->
<script>
window.addEventListener("load", () => sslide({
  target: document.getElementById("demo"),
  images: [
    {src: "slide-a.webp", cap: "Girl eating flower in library."},
    {src: "slide-b.webp", cap: "Girl eating cactus."},
    {src: "slide-c.webp", cap: "Girl eating seafood in sea."}
  ],
  auto: 3000 // (optional) 3 sec per slide, remove to manual scroll
}));
</script>

1. Captain Obvious at your service, load both slides.css and slides.js.
2. Define a <div> to attach the slideshow to.
3. Lastly, use sslide() to attach the slideshow. There are only 3 options here:
   • target The <div> element that you want to attach the slideshow to.
   • images Array of images you want to show. Remember to provide both the source URL and caption.
   • auto In milliseconds, optional. Automatically rotate between the slides.

 

 

 

PART 1) ATTACH HTML INTERFACE

function sslide (instance) {
  // (A) BUILD HTML INTERFACE
  var sImg = document.createElement("img"),
      sCaption = document.createElement("div"),
      sLeft = document.createElement("div"),
      sRight = document.createElement("div");
      instance.target.className = "sSlide hide";
      sImg.className = "sImg";
      sCaption.className = "sCaption";
      sLeft.className = "sLeft";
      sRight.className = "sRight";
      sLeft.innerHTML = "<";
      sRight.innerHTML = ">";
  instance.target.appendChild(sImg);
  instance.target.appendChild(sCaption);
  instance.target.appendChild(sLeft);
  instance.target.appendChild(sRight);
  // ...
}

Ok, this looks crazy. But all it does is essentially generate the following HTML:

<div id="demo" class="sSlide hide">
  <div class="sImg"></div>
  <div class="sCaption"></div>
  <div class="sLeft" onclick="shift()"></div>
  <div class="sRight" onclick="shift(1)"></div>
</div>

Take note of the hide CSS class here. We will not show the slideshow until all images are properly loaded.

 

 

PART 2) SHIFT SLIDE

// (B) AUTO SHIFT SLIDE
if (instance.auto) {
  var auto = () => {
    if (instance.timer) { clearInterval(instance.timer); }
    instance.timer = setInterval(() => shift(1), instance.auto);
  };
}

// (C) SHIFT SLIDE
instance.now = -1; // current slide
var shift = direction => {
  // (C1) CALCULATE NEXT SLIDE
  if (direction) { instance.now++; } else { instance.now--; }
  if (instance.now < 0) { instance.now = instance.images.length - 1; }
  if (instance.now >= instance.images.length) { instance.now = 0; }
 
  // (C2) DRAW SLIDE
  sImg.src = instance.images[instance.now].src;
  sCaption.innerHTML = instance.images[instance.now].cap;
 
  // (C3) AUTO SHIFT SLIDE
  if (instance.auto) { auto(); }
}
sLeft.onclick = () => shift();
sRight.onclick = () => shift(1);

Should not be much trouble.

• We use instance.now to track the current slide.
• When the user clicks on last/next, we subtract/add instance.now accordingly.
• Then, set the image and caption.

 

PART 3) PRELOAD IMAGES

// (D) PRELOAD IMAGES
var loaded = 0;
for (let i of instance.images) {
  let img = new Image();
  img.src = i.src;
  img.onload = () => {
    loaded++;
    if (loaded == instance.images.length) {
      shift(1);
      instance.target.classList.remove("hide");
      if (instance.auto) { auto(); }
    }
  };
}

To prevent “missing slides”, this little snippet will wait until all images are loaded before showing the slideshow.

 

 

PART 4) THE CSS

/* (A) WHOLE PAGE */
* {
  font-family: Arial, Helvetica, sans-serif;
  box-sizing: border-box;
}
 
/* (B) SHARED */
.sImg, .sCaption { width: 100%; }
.sSlide, .sLeft, .sRight { display: flex; }
 
/* (C) CONTAINER */
.sSlide {
  flex-wrap: wrap;
  position: relative;
  max-width: 640px;
}
 
/* (D) IMAGE */
.sImg {
  height: 350px;
  object-fit: cover; /* fill, contain, scale-down */
}

/* (E) CAPTION */
.sCaption {
  padding: 10px;
  color: #fff;
  background: #000;
}
 
/* (F) CONTROLS */
/* (F1) LEFT/RIGHT BUTTONS */
.sLeft, .sRight {
  align-items: center;
  position: absolute;
  top: 0;
  z-index: 9;
  height: 100%;
  padding: 0 20px;
  font-size: 2em;
  color: #fff;
  background: rgba(0, 0, 0, 0.5);
  cursor: pointer;
}
.sTop .sLeft { left: 0; }
.sTop .sRight { right: 0; }
 
/* (F2) SHOW ONLY ON HOVER */
.sLeft, .sRight {
  visibility: hidden;
  opacity: 0;
  transition: opacity 0.3s;
}
.sSlide:hover .sLeft, .sSlide:hover .sRight {
  visibility: visible;
  opacity: 1;
}

Yep… Don’t think I want to dive too deep into the CSS – These are practically the cosmetics of the slideshow. Feel free to change the colors and layout to fit your own theme.

 

 

 

USING PHP TO AUTOLOAD ALL SLIDES

Lazy to change the HTML every time? Use a server-side script to help you extract all the image files automatically. Here’s a quick example in PHP.

<script>
window.addEventListener("DOMContentLoaded", () => {
  sslide.init({
    target: "slidedemo",
    images: [<?php
      $dir = "gallery/";
      $images = glob($dir . "*.{jpg,jpeg,gif,png,bmp,webp}", GLOB_BRACE);
      $all = count($images);
      $last = $all - 1;
      for ($i=0; $i<$all; $i++) {
        printf('{src:"%s%s", cap:"%s"}%s',
          $dir, basename($images[$i]), basename($images[$i]),
          $i==$last ? "" : ","
        );
      }
    ?>]
});
</script>

 

COMPATIBILITY CHECKS

• Arrow Functions – CanIUse
• CSS Flexbox – CanIUse

Should work across all major browsers… Less the “ancient ones”.

 

LINKS & REFERENCES

• Example on CodePen – Simple Responsive Slideshow