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image slide show with both automated and manual controls

The code runs quite well, the only issue i'm experiencing is that it doesn't start until its initiated with the control button. I need it to start sliding as soon as the page is loaded, I think it has to do with the display but i'm not quite sure. Kindly go through my code below and correct as appropriate i'll go to the stars and back to make sacrifices for the pandemic to be over if I get a solution
var slideIndex = 0;
var slides = document.getElementsByClassName("mySlides");
showSlides();
function showSlides() {
var i;
for (i = 0; i < slides.length; i++) {
slides[i].style.display = "none";
}
slideIndex++;
if (slideIndex> slides.length) {slideIndex = 1}
slides[slideIndex-1].style.display = "block";
setTimeout(showSlides, 5000); // Change image every 5 seconds
}
function currentSlide(no) {
var i;
for (i = 0; i < slides.length; i++) {
slides[i].style.display = "none";
}
slideIndex = no;
slides[no-1].style.display = "block";
}
function plusSlides(n) {
var newslideIndex = slideIndex + n;
if(newslideIndex < 4 && newslideIndex > 0){
currentSlide(newslideIndex);
}
}
* {box-sizing:border-box}
/* Slideshow container */
.slideshow-container {
max-width: 1000px;
position: relative;
margin: auto;
}
.mySlides {
display: none;
}
/* Next & previous buttons */
.prev, .next {
cursor: pointer;
position: absolute;
top: 50%;
width: auto;
margin-top: -22px;
padding: 16px;
color: white;
font-weight: bold;
font-size: 18px;
transition: 0.6s ease;
border-radius: 0 3px 3px 0;
}
/* Position the "next button" to the right */
.next {
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);
}
/* Caption text */
.text {
color: #f2f2f2;
font-size: 15px;
padding: 8px 12px;
position: absolute;
bottom: 8px;
width: 100%;
text-align: center;
}
/* Number text (1/3 etc) */
.numbertext {
color: #f2f2f2;
font-size: 12px;
padding: 8px 12px;
position: absolute;
top: 0;
}
/* The dots/bullets/indicators */
.dot {
cursor:pointer;
height: 13px;
width: 13px;
margin: 0 2px;
background-color: #bbb;
border-radius: 50%;
display: inline-block;
transition: background-color 0.6s ease;
}
.active, .dot:hover {
background-color: #717171;
}
/* Fading animation */
.fade {
-webkit-animation-name: fade;
-webkit-animation-duration: 1.5s;
animation-name: fade;
animation-duration: 1.5s;
}
#-webkit-keyframes fade {
from {display: block;}
to {margin: 0;}
}
#keyframes fade {
from {opacity: .4}
to {opacity: 1}
}
<div class="slideshow-container">
<div class="mySlides fade">
<div class="numbertext">1 / 3</div>
<div style="width:100%;background-color: yellow;height:50px;"> </div>
<div class="text">Caption Text</div>
</div>
<div class="mySlides fade">
<div class="numbertext">2 / 3</div>
<div style="width:100%;background-color: black;height: 50px; "> </div>
<div class="text">Caption Two</div>
</div>
<div class="mySlides fade">
<div class="numbertext">3 / 3</div>
<div style="width:100%;background-color: blue;height: 50px;"> </div>
<div class="text">Caption Three</div>
</div>
<a class="prev" onclick="plusSlides(-1)">❮</a>
<a class="next" onclick="plusSlides(1)">❯</a>
</div>
<br>
<div style="text-align:center">
<span class="dot" onclick="currentSlide(1)"></span>
<span class="dot" onclick="currentSlide(2)"></span>
<span class="dot" onclick="currentSlide(3)"></span>
</div>

Can't implement the W3Schools slideshow in Bootstrap?

I'm trying to edit my Bootstrap and I want to add more stuff then what it already has but it isn't working.
I tried to add a slideshow, but it is completely white, only the arrows to change the image are blue.
I know part of it is working because when I click to change the image, the dimensions of the page change (I only have 1 photo, the others 2 links are for photos that don't exist).
I copied the W3Schools code and pasted it in the bootstrap page, is something in the bootstrap file, putting everything white?
Here is my code:
var slideIndex = 1;
showSlides(slideIndex);
// Next/previous controls
function plusSlides(n) {
showSlides(slideIndex += n);
}
// Thumbnail image controls
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";
}
* {
box-sizing: border-box
}
/* Slideshow container */
.slideshow-container {
max-width: 1000px;
position: relative;
margin: auto;
}
/* Hide the images by default */
.mySlides {
display: none;
z-index: 3;
}
/* Next & previous buttons */
.prev, .next {
cursor: pointer;
position: absolute;
top: 50%;
width: auto;
margin-top: -22px;
padding: 16px;
color: white;
font-weight: bold;
font-size: 18px;
transition: 0.6s ease;
border-radius: 0 3px 3px 0;
user-select: none;
}
/* Position the "next button" to the right */
.next {
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);
}
/* Caption text */
.text {
color: #f2f2f2;
font-size: 15px;
padding: 8px 12px;
position: absolute;
bottom: 8px;
width: 100%;
text-align: center;
}
/* Number text (1/3 etc) */
.numbertext {
color: #f2f2f2;
font-size: 12px;
padding: 8px 12px;
position: absolute;
top: 0;
}
/* 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;
}
.active, .dot:hover {
background-color: #717171;
}
/* Fading animation */
.fade {
-webkit-animation-name: fade;
-webkit-animation-duration: 1.5s;
animation-name: fade;
animation-duration: 1.5s;
}
#-webkit-keyframes fade {
from {
opacity: .4
}
to {
opacity: 1
}
}
#keyframes fade {
from {
opacity: .4
}
to {
opacity: 1
}
}
}
<!-- Slideshow container -->
<div class="slideshow-container">
<!-- Full-width images with number and caption text -->
<div class="mySlides fade">
<div class="numbertext">1 / 3</div>
<img src="~/Photo/Test1.png" style="width:100%">
<div class="text">Caption Text</div>
</div>
<div class="mySlides fade">
<div class="numbertext">2 / 3</div>
<img src="img2.jpg" style="width:100%">
<div class="text">Caption Two</div>
</div>
<div class="mySlides fade">
<div class="numbertext">3 / 3</div>
<img src="img3.jpg" style="width:100%">
<div class="text">Caption Three</div>
</div>
<!-- Next and previous buttons -->
<a class="prev" onclick="plusSlides(-1)">❮</a>
<a class="next" onclick="plusSlides(1)">❯</a>
</div>
<br>
<!-- The dots/circles -->
<div style="text-align:center">
<span class="dot" onclick="currentSlide(1)"></span>
<span class="dot" onclick="currentSlide(2)"></span>
<span class="dot" onclick="currentSlide(3)"></span>
</div>

As per your question, when you add bootstrap to the code the images are being displayed in white color as your code is getting effected by class="fade" as it's overlapping with bootstrap fade class. Use a different class name
var slideIndex = 1;
showSlides(slideIndex);
// Next/previous controls
function plusSlides(n) {
showSlides(slideIndex += n);
}
// Thumbnail image controls
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";
}
* {
box-sizing: border-box
}
/* Slideshow container */
.slideshow-container {
max-width: 1000px;
position: relative;
margin: auto;
}
/* Hide the images by default */
.mySlides {
display: none;
z-index: 3;
}
/* Next & previous buttons */
.prev, .next {
cursor: pointer;
position: absolute;
top: 50%;
width: auto;
margin-top: -22px;
padding: 16px;
color: white;
font-weight: bold;
font-size: 18px;
transition: 0.6s ease;
border-radius: 0 3px 3px 0;
user-select: none;
}
/* Position the "next button" to the right */
.next {
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);
}
/* Caption text */
.text {
color: #f2f2f2;
font-size: 15px;
padding: 8px 12px;
position: absolute;
bottom: 8px;
width: 100%;
text-align: center;
}
/* Number text (1/3 etc) */
.numbertext {
color: #f2f2f2;
font-size: 12px;
padding: 8px 12px;
position: absolute;
top: 0;
}
/* 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;
}
.active, .dot:hover {
background-color: #717171;
}
/* Fading animation */
.fade-in {
-webkit-animation-name: fade;
-webkit-animation-duration: 1.5s;
animation-name: fade;
animation-duration: 1.5s;
}
#-webkit-keyframes fade {
from {
opacity: .4
}
to {
opacity: 1
}
}
#keyframes fade {
from {
opacity: .4
}
to {
opacity: 1
}
}
}
<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Example</title>
<meta charset="utf-8">
<meta content="width=device-width, initial-scale=1" name="viewport">
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.0/css/bootstrap.min.css" rel="stylesheet">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.0/jquery.min.js">
</script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.0/js/bootstrap.min.js">
</script>
</head>
<body>
<div class="slideshow-container">
<!-- Full-width images with number and caption text -->
<div class="mySlides fade-in">
<div class="numbertext">
1 / 3
</div><img src="https://www.w3schools.com/bootstrap/ny.jpg" style="width:100%">
<div class="text">
Caption Text
</div>
</div>
<div class="mySlides fade-in">
<div class="numbertext">
2 / 3
</div><img src="https://www.w3schools.com/bootstrap/chicago.jpg" style="width:100%">
<div class="text">
Caption Two
</div>
</div>
<div class="mySlides fade-in">
<div class="numbertext">
3 / 3
</div><img src="https://www.w3schools.com/bootstrap/la.jpg" style="width:100%">
<div class="text">
Caption Three
</div>
</div><!-- Next and previous buttons -->
<a class="prev" onclick="plusSlides(-1)">❮</a> <a class="next" onclick="plusSlides(1)">❯</a>
</div><br>
<!-- The dots/circles -->
<div style="text-align:center">
<span class="dot" onclick="currentSlide(1)"></span> <span class="dot" onclick="currentSlide(2)"></span> <span class="dot" onclick="currentSlide(3)"></span>
</div>
</body>
</html>

The most logical reason seems to be that the path of the image being displayed in carousel/slideshow is not correct.
When the page is loaded, open the developer tools and in the html, search for Photo/Test1.png, there would be a path in the src tag.
Verify that the path is correct. Open the link in a new tab to verify that the image in-fact is loading at the URL and do the same for other images you are using.
You can also try to use absolute paths as the image src attribute, for example:
https://www.w3schools.com/howto/img_snow_wide.jpg
https://www.w3schools.com/howto/img_mountains_wide.jpg
https://www.w3schools.com/howto/img_nature_wide.jpg
If that loads the images than it surely is an issue with path you are using.

First image of slideshow does not load

I've just started with CSS and JavaScript, and I tried to make an image slider by looking into w3schools. The slider works, but the first image always comes empty only with the navigation bars being visible.but once I click the next button, it works fine.I'm not understanding what to change with this. Here's the code.
'use strict';
var slideIndex = 1;
function plusSlides(n) {
showSlides(slideIndex += n);
}
function currentSlide(n) {
showSlides(slideIndex = n);
}
function showSlides(n) {
//alert('showslides('+ n +')\nslideIndex='+slideIndex);
var i;
var slides = document.getElementsByClassName("mySlides");
var dots = document.getElementsByClassName("dot");
if (n === undefined) {
n = ++slideIndex;
}
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";
setTimeout(showSlides, 5000); // Change image every 5 seconds
}
* {
box-sizing: border-box;
}
body {
font-family: Verdana, sans-serif;
margin: 0
}
.mySlides {
display: none;
}
img {
vertical-align: middle;
}
/* Slideshow container */
.slideshow-container {
max-width: 1000px;
position: relative;
margin: auto;
}
/* Next & previous buttons */
.prev,
.next {
cursor: pointer;
position: absolute;
top: 50%;
width: auto;
padding: 16px;
margin-top: -22px;
color: white;
font-weight: bold;
font-size: 18px;
transition: 0.6s ease;
border-radius: 0 3px 3px 0;
}
/* Position the "next button" to the right */
.next {
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);
}
/* Caption text */
.text {
color: #f2f2f2;
font-size: 15px;
padding: 8px 12px;
position: absolute;
bottom: 8px;
width: 100%;
text-align: center;
}
/* Number text (1/3 etc) */
.numbertext {
color: #f2f2f2;
font-size: 12px;
padding: 8px 12px;
position: absolute;
top: 0;
}
/* 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;
}
.active,
.dot:hover {
background-color: #717171;
}
/* Fading animation */
.fade {
-webkit-animation-name: fade;
-webkit-animation-duration: 1.5s;
animation-name: fade;
animation-duration: 1.5s;
}
#-webkit-keyframes fade {
from {
opacity: .4
}
to {
opacity: 1
}
}
#keyframes fade {
from {
opacity: .4
}
to {
opacity: 1
}
}
/* On smaller screens, decrease text size */
#media only screen and (max-width: 300px) {
.prev,
.next,
.text {
font-size: 11px
}
}
<body>
<?php
include './p1.php';
// put your code here
?>
<div class="slideshow-container">
<div class="mySlides fade">
<div class="numbertext">1 / 3</div>
<img src="pics/bali2.jpg" height="400px" width="800px">
<div class="text">Caption Text</div>
</div>
<div class="mySlides fade">
<div class="numbertext">2 / 3</div>
<img src="pics/brazil1.jpg" height="400px" width="800px">
<div class="text">Caption Two</div>
</div>
<div class="mySlides fade">
<div class="numbertext">3 / 3</div>
<img src="pics/germany.jpg" height="400px" width="800px">
<div class="text">Caption Three</div>
</div>
<a class="prev" onclick="plusSlides(-1)">❮</a>
<a class="next" onclick="plusSlides(1)">❯</a>
</div>
<br>
<div style="text-align:center">
<span class="dot" onclick="currentSlide(1)"></span>
<span class="dot" onclick="currentSlide(2)"></span>
<span class="dot" onclick="currentSlide(3)"></span>
</div>
</body>

The slider works, but the first image always comes empty only with the navigation bars being visible
Just because of you apply css this mySlides on your, so your all div not visble. When you are click on next or previous or slider so particular container are showing.
So you need to apply the style="display: block;" on your first div.
DEMO
var slideIndex = 1,
interval;
function stopAndStart() {
if (interval) {
clearInterval(interval)
}
interval = setInterval(showSlides, 5000); // Change image every 5 seconds;
}
function plusSlides(n) {
showSlides(slideIndex += n);
stopAndStart()
}
function currentSlide(n) {
showSlides(slideIndex = n);
stopAndStart()
}
function showSlides(n) {
var i,
slides = document.getElementsByClassName("mySlides"),
dots = document.getElementsByClassName("dot");
if (n === undefined) {
n = ++slideIndex;
}
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";
}
stopAndStart();
body {
font-family: Verdana, sans-serif;
margin: 0
}
.mySlides {
display: none;
text-align: center;
}
img {
vertical-align: middle;
}
/* Slideshow container */
.slideshow-container {
max-width: 1000px;
position: relative;
margin: auto;
background: burlywood;
}
/* Next & previous buttons */
.prev,
.next {
cursor: pointer;
position: absolute;
top: 50%;
width: auto;
padding: 16px;
margin-top: -22px;
color: white;
font-weight: bold;
font-size: 18px;
transition: 0.6s ease;
border-radius: 0 3px 3px 0;
}
/* Position the "next button" to the right */
.next {
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);
}
/* Caption text */
.text {
color: #f2f2f2;
font-size: 15px;
padding: 8px 12px;
position: absolute;
bottom: 8px;
width: 100%;
text-align: center;
}
/* Number text (1/3 etc) */
.numbertext {
color: #f2f2f2;
font-size: 12px;
padding: 8px 12px;
position: absolute;
top: 0;
}
/* 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;
}
.active,
.dot:hover {
background-color: #717171;
}
/* Fading animation */
.fade {
-webkit-animation-name: fade;
-webkit-animation-duration: 1.5s;
animation-name: fade;
animation-duration: 1.5s;
}
#-webkit-keyframes fade {
from {
opacity: .4
}
to {
opacity: 1
}
}
#keyframes fade {
from {
opacity: .4
}
to {
opacity: 1
}
}
/* On smaller screens, decrease text size */
#media only screen and (max-width: 300px) {
.prev,
.next,
.text {
font-size: 11px
}
}
<div class="slideshow-container">
<div class="mySlides fade" style="display: block;">
<div class="numbertext">1 / 3</div>
<img src="https://dummyimage.com/400x400/555985/fff&text=1">
<div class="text">Caption Text</div>
</div>
<div class="mySlides fade">
<div class="numbertext">2 / 3</div>
<img src="https://dummyimage.com/400x400/555985/fff&text=2">
<div class="text">Caption Two</div>
</div>
<div class="mySlides fade">
<div class="numbertext">3 / 3</div>
<img src="https://dummyimage.com/400x400/555985/fff&text=3">
<div class="text">Caption Three</div>
</div>
<a class="prev" onclick="plusSlides(-1)">❮</a>
<a class="next" onclick="plusSlides(1)">❯</a>
</div>
<br>
<div style="text-align:center">
<span class="dot active" onclick="currentSlide(1)"></span>
<span class="dot" onclick="currentSlide(2)"></span>
<span class="dot" onclick="currentSlide(3)"></span>
</div>

Image in slider dissapear after few seconds

I'm implementing a simple image slider in my Middleman project. The images show up and the bullets are clickable. The images are linked with image_tags in Middleman. However, after an image appears it disappears after a few seconds! The only thing I could find which could have an effect on this would be the fade-in option.
After extensively looking with the inspector I couldn't find anything which causes the image not to show up.
Below my current code.
HTML
<div class="slideshow-container">
<!-- Full-width images with number and caption text -->
<div class="mySlides fade">
<div class="numbertext">1 / 3</div>
<%= image_tag "img3.jpeg", :class => "slider-img"%>
<div class="text">Caption Text</div>
</div>
<div class="mySlides fade">
<div class="numbertext">2 / 3</div>
<%= image_tag "img3.jpeg", :class => "slider-img"%>
<div class="text">Caption Two</div>
</div>
<div class="mySlides fade">
<div class="numbertext">3 / 3</div>
<%= image_tag "img3.jpeg", :class => "slider-img"%>
<div class="text">Caption Three</div>
</div>
<!-- Next and previous buttons -->
<a class="prev" onclick="plusSlides(-1)">❮</a>
<a class="next" onclick="plusSlides(1)">❯</a>
</div>
<br>
<!-- The dots/circles -->
<div style="text-align:center">
<span class="dot" onclick="currentSlide(1)"></span>
<span class="dot" onclick="currentSlide(2)"></span>
<span class="dot" onclick="currentSlide(3)"></span>
</div>
CSS
* {box-sizing:border-box}
/* Slideshow container */
.slideshow-container {
max-width: 1000px;
position: relative;
margin: auto;
}
/* Hide the images by default */
.mySlides {
display: none;
}
/* Next & previous buttons */
.prev, .next {
cursor: pointer;
position: absolute;
top: 50%;
width: auto;
margin-top: -22px;
padding: 16px;
color: white;
font-weight: bold;
font-size: 18px;
transition: 0.6s ease;
border-radius: 0 3px 3px 0;
}
/* Position the "next button" to the right */
.next {
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);
}
/* Caption text */
.text {
color: #f2f2f2;
font-size: 15px;
padding: 8px 12px;
position: absolute;
bottom: 8px;
width: 100%;
text-align: center;
}
/* Number text (1/3 etc) */
.numbertext {
color: #f2f2f2;
font-size: 12px;
padding: 8px 12px;
position: absolute;
top: 0;
}
/* 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;
}
.active, .dot:hover {
background-color: #717171;
}
/* Fading animation */
.fade {
-webkit-animation-name: fade;
-webkit-animation-duration: 1.5s;
animation-name: fade;
animation-duration: 1.5s;
}
#-webkit-keyframes fade {
from {opacity: .4}
to {opacity: 1}
}
#keyframes fade {
from {opacity: .4}
to {opacity: 1}
}
.slider-img {
width: 100%;
}
JS
var slideIndex = 1;
showSlides(slideIndex);
// Next/previous controls
function plusSlides(n) {
showSlides(slideIndex += n);
}
// Thumbnail image controls
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";
}

I try your code in fiddle and it's work fine :
Here is my fiddle http://jsfiddle.net/numa1x39/8/
var slideIndex = 1;
showSlides(slideIndex);
// Next/previous controls
function plusSlides(n) {
showSlides(slideIndex += n);
}
// Thumbnail image controls
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";
}
* {box-sizing:border-box}
/* Slideshow container */
.slideshow-container {
max-width: 1000px;
position: relative;
margin: auto;
}
/* Hide the images by default */
.mySlides {
display: none;
}
/* Next & previous buttons */
.prev, .next {
cursor: pointer;
position: absolute;
top: 50%;
width: auto;
margin-top: -22px;
padding: 16px;
color: white;
font-weight: bold;
font-size: 18px;
transition: 0.6s ease;
border-radius: 0 3px 3px 0;
}
/* Position the "next button" to the right */
.next {
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);
}
/* Caption text */
.text {
color: #f2f2f2;
font-size: 15px;
padding: 8px 12px;
position: absolute;
bottom: 8px;
width: 100%;
text-align: center;
}
/* Number text (1/3 etc) */
.numbertext {
color: #f2f2f2;
font-size: 12px;
padding: 8px 12px;
position: absolute;
top: 0;
}
/* 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;
}
.active, .dot:hover {
background-color: #717171;
}
/* Fading animation */
.fade {
-webkit-animation-name: fade;
-webkit-animation-duration: 1.5s;
animation-name: fade;
animation-duration: 1.5s;
}
#-webkit-keyframes fade {
from {opacity: .4}
to {opacity: 1}
}
#keyframes fade {
from {opacity: .4}
to {opacity: 1}
}
.slider-img {
width: 100%;
}
<div class="slideshow-container">
<!-- Full-width images with number and caption text -->
<div class="mySlides fade">
<div class="numbertext">1 / 3</div>
<img src="https://static2.farakav.com/files/pictures/thumb/01125088.jpg" class="slider-img">
<div class="text">Caption Text</div>
</div>
<div class="mySlides fade">
<div class="numbertext">2 / 3</div>
<img src="https://static2.farakav.com/files/pictures/thumb/01324464.jpg" class="slider-img">
<div class="text">Caption Two</div>
</div>
<div class="mySlides fade">
<div class="numbertext">3 / 3</div>
<img src="https://static2.farakav.com/files/pictures/thumb/01324567.jpg" class="slider-img">
<div class="text">Caption Three</div>
</div>
<!-- Next and previous buttons -->
<a class="prev" onclick="plusSlides(-1)">❮</a>
<a class="next" onclick="plusSlides(1)">❯</a>
</div>
<br>
<!-- The dots/circles -->
<div style="text-align:center">
<span class="dot" onclick="currentSlide(1)"></span>
<span class="dot" onclick="currentSlide(2)"></span>
<span class="dot" onclick="currentSlide(3)"></span>
</div>
</div>

Creating a Slideshow in different files

This is the html code
<!DOCTYPE html>
<html>
<head>
<title></title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" type="text/css" href="style2.css">
<script src="learn1.js"</script>
</head>
<body>
<div class="slideshow-container">
<div class="mySlides fade">
<div class="numbertext">1 / 3</div>
<img src="learnimg/1.jpg" style="width:100%">
<div class="text">Caption Text</div>
</div>
<div class="mySlides fade">
<div class="numbertext">2 / 3</div>
<img src="learnimg/2.jpg" style="width:100%">
<div class="text">Caption Two</div>
</div>
<div class="mySlides fade">
<div class="numbertext">3 / 3</div>
<img src="learnimg/3.jpg" style="width:100%">
<div class="text">Caption Three</div>
</div>
<a class="prev" onclick="plusSlides(-1)">?</a>
<a class="next" onclick="plusSlides(1)">?</a>
</div>
<br>
<div style="text-align:center">
<span class="dot" onclick="currentSlide(1)"></span>
<span class="dot" onclick="currentSlide(2)"></span>
<span class="dot" onclick="currentSlide(3)"></span>
</div>
</body>
</html>`
This is the css code
* {box-sizing:border-box} body {font-family: Verdana,sans-serif;margin:0}
/* Slideshow container */ .slideshow-container { max-width: 1000px;
position: relative; margin: auto; }
/* Next & previous buttons */ .prev, .next { cursor: pointer;
position: absolute; top: 0; top: 50%; width: auto; padding:
16px; margin-top: -22px; color: white; font-weight: bold;
font-size: 18px; transition: 0.6s ease; border-radius: 0 3px 3px
0; }
/* Position the "next button" to the right */ .next { 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); }
/* Caption text */ .text { color: #f2f2f2; font-size: 15px;
padding: 8px 12px; position: absolute; bottom: 8px; width: 100%;
text-align: center; }
/* Number text (1/3 etc) */ .numbertext { color: #f2f2f2;
font-size: 12px; padding: 8px 12px; position: absolute; top: 0;
}
/* The dots/bullets/indicators */ .dot { cursor:pointer; height:
13px; width: 13px; margin: 0 2px; background-color: #bbb;
border-radius: 50%; display: inline-block; transition:
background-color 0.6s ease; }
.active, .dot:hover { background-color: #717171; }
/* Fading animation */ .fade { -webkit-animation-name: fade;
-webkit-animation-duration: 1.5s; animation-name: fade; animation-duration: 1.5s; }
#-webkit-keyframes fade { from {opacity: .4} to {opacity: 1} }
#keyframes fade { from {opacity: .4} to {opacity: 1} }
/* On smaller screens, decrease text size */ #media only screen and
(max-width: 300px) { .slprev, .slnext,.text {font-size: 11px} }
This is the javascript code
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"; }
All these 3 codes are in different files. This is basically for the creation of a simple slideshow of three images. But when I execute this(all in different files) there is nothing to display(white screen in the browser). But when executed in a single html file(all contents in a single file) there is a perfect slideshow.
I cannot figure out this problem. Please help me out with this.

This doesn't seem right :
<script src="learn1.js"</script>
You forgot to close the opening tag, as such :
<script src="learn1.js"></script>
Plus, it's always a good habit to specify your resource type :
<script type="text/javascript" src="learn1.js"></script>

The code you posted seems to work just fine.
Maybe the image files isn't where you say they are?
Try opening the console and look for errors.
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";
}
{
box-sizing: border-box
}
body {
font-family: Verdana, sans-serif;
margin: 0
}
/* Slideshow container */
.slideshow-container {
max-width: 1000px;
position: relative;
margin: auto;
}
/* Next & previous buttons */
.prev,
.next {
cursor: pointer;
position: absolute;
top: 0;
top: 50%;
width: auto;
padding: 16px;
margin-top: -22px;
color: white;
font-weight: bold;
font-size: 18px;
transition: 0.6s ease;
border-radius: 0 3px 3px 0;
}
/* Position the "next button" to the right */
.next {
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);
}
/* Caption text */
.text {
color: #f2f2f2;
font-size: 15px;
padding: 8px 12px;
position: absolute;
bottom: 8px;
width: 100%;
text-align: center;
}
/* Number text (1/3 etc) */
.numbertext {
color: #f2f2f2;
font-size: 12px;
padding: 8px 12px;
position: absolute;
top: 0;
}
/* The dots/bullets/indicators */
.dot {
cursor: pointer;
height: 13px;
width: 13px;
margin: 0 2px;
background-color: #bbb;
border-radius: 50%;
display: inline-block;
transition: background-color 0.6s ease;
}
.active,
.dot:hover {
background-color: #717171;
}
/* Fading animation */
.fade {
-webkit-animation-name: fade;
-webkit-animation-duration: 1.5s;
animation-name: fade;
animation-duration: 1.5s;
}
#-webkit-keyframes fade {
from {
opacity: .4
}
to {
opacity: 1
}
}
#keyframes fade {
from {
opacity: .4
}
to {
opacity: 1
}
}
/* On smaller screens, decrease text size */
#media only screen and (max-width: 300px) {
.slprev,
.slnext,
.text {
font-size: 11px
}
}
<div class="slideshow-container">
<div class="mySlides fade">
<div class="numbertext">1 / 3</div>
<img src="https://placeholdit.imgix.net/~text?txtsize=60&txt=1&w=100&h=100" style="width:100%">
<div class="text">Caption Text</div>
</div>
<div class="mySlides fade">
<div class="numbertext">2 / 3</div>
<img src="https://placeholdit.imgix.net/~text?txtsize=60&txt=2&w=100&h=100" style="width:100%">
<div class="text">Caption Two</div>
</div>
<div class="mySlides fade">
<div class="numbertext">3 / 3</div>
<img src="https://placeholdit.imgix.net/~text?txtsize=60&txt=3&w=100&h=100" style="width:100%">
<div class="text">Caption Three</div>
</div>
<a class="prev" onclick="plusSlides(-1)">❮</a>
<a class="next" onclick="plusSlides(1)">❯</a>
</div>
<br>
<div style="text-align:center">
<span class="dot" onclick="currentSlide(1)"></span>
<span class="dot" onclick="currentSlide(2)"></span>
<span class="dot" onclick="currentSlide(3)"></span>
</div>