Develop Reference

Add 2-3 images in the mouse hover effect

I have made this code for mouse hover zoom effect and it is working without error. But I want to add 2-3 images so as the user clicks on it, then that image is shown and mouse hover effect works on it, i.e. on hovering the mouse on the picture shows a zoom effect.
Here is my code:
function imageZoom(imgID, resultID) {
var img, lens, result, cx, cy;
img = document.getElementById(imgID);
result = document.getElementById(resultID);
/*create lens:*/
lens = document.createElement("DIV");
lens.setAttribute("class", "img-zoom-lens");
/*insert lens:*/
img.parentElement.insertBefore(lens, img);
/*calculate the ratio between result DIV and lens:*/
cx = result.offsetWidth / lens.offsetWidth;
cy = result.offsetHeight / lens.offsetHeight;
/*set background properties for the result DIV:*/
result.style.backgroundImage = "url('" + img.src + "')";
result.style.backgroundSize = (img.width * cx) + "px " + (img.height * cy) + "px";
/*execute a function when someone moves the cursor over the image, or the lens:*/
lens.addEventListener("mousemove", moveLens);
img.addEventListener("mousemove", moveLens);
/*and also for touch screens:*/
lens.addEventListener("touchmove", moveLens);
img.addEventListener("touchmove", moveLens);
/*initialise and hide lens result*/
result.style.display = "none";
/*Reveal and hide on mouseover or out*/
lens.onmouseover = function(){result.style.display = "block";};
lens.onmouseout = function(){result.style.display = "none";};
function moveLens(e) {
var pos, x, y;
/*prevent any other actions that may occur when moving over the image:*/
e.preventDefault();
/*get the cursor's x and y positions:*/
pos = getCursorPos(e);
/*calculate the position of the lens:*/
x = pos.x - (lens.offsetWidth / 2);
y = pos.y - (lens.offsetHeight / 2);
/*prevent the lens from being positioned outside the image:*/
if (x > img.width - lens.offsetWidth) {x = img.width - lens.offsetWidth;}
if (x < 0) {x = 0;}
if (y > img.height - lens.offsetHeight) {y = img.height - lens.offsetHeight;}
if (y < 0) {y = 0;}
/*set the position of the lens:*/
lens.style.left = x + "px";
lens.style.top = y + "px";
/*display what the lens "sees":*/
result.style.backgroundPosition = "-" + (x * cx) + "px -" + (y * cy) + "px";
}
function getCursorPos(e) {
var a, x = 0, y = 0;
e = e || window.event;
/*get the x and y positions of the image:*/
a = img.getBoundingClientRect();
/*calculate the cursor's x and y coordinates, relative to the image:*/
x = e.pageX - a.left;
y = e.pageY - a.top;
/*consider any page scrolling:*/
x = x - window.pageXOffset;
y = y - window.pageYOffset;
return {x : x, y : y};
}
};
imageZoom("myimage", "myresult");
* {box-sizing: border-box;}
.img-zoom-container {
position: relative;
display: flex;
}
.img-zoom-lens {
position: absolute;
border: 1px solid #d4d4d4;
/*set the size of the lens:*/
width: 40px;
height: 40px;
}
.img-zoom-result {
border: 1px solid #d4d4d4;
position: absolute;
left: 300px; /*match width of #myimage*/
/*set the size of the result div:*/
width: 300px;
height: 300px;
}
<h1>Image Zoom</h1>
<p>Mouse over the image:</p>
<div class="img-zoom-container">
<img id="myimage" src="https://hatrabbits.com/wp-content/uploads/2018/10/risky-assumptions.jpg" width="300" height="240">
<div id="myresult" class="img-zoom-result" style=""></div>
</div>
<p>The image must be placed inside a container with relative positioning.</p>
<p>The result can be put anywhere on the page, but must have the class name "img-zoom-result".</p>
<p>Make sure both the image and the result have IDs. These IDs are used when a javaScript initiates the zoom effect.</p>
I was searching for the answer and hope here i will get the solution.
Thank you in advance.

Just add more picture like this:
<div class="img-zoom-container">
<img id="myimage" src="https://hatrabbits.com/wp-content/uploads/2018/10/risky-assumptions.jpg" width="300" height="240">
<div id="myresult" class="img-zoom-result" style=""></div>
</div>
<div class="img-zoom-container">
<img id="myimage2" src="https://hatrabbits.com/wp-content/uploads/2018/10/risky-assumptions.jpg" width="300" height="240">
<div id="myresult2" class="img-zoom-result" style=""></div>
</div>
<div class="img-zoom-container">
<img id="myimage3" src="https://hatrabbits.com/wp-content/uploads/2018/10/risky-assumptions.jpg" width="300" height="240">
<div id="myresult3" class="img-zoom-result" style=""></div>
</div>
Then add more calling function
imageZoom("myimage", "myresult");
imageZoom("myimage2", "myresult2");
imageZoom("myimage3", "myresult3");
;)

img {
height: 100px;
width: 200px;
background-color: blue;
}
img:hover {
height: 200px;
width: 400px;
background-color: red;
}
<img src="">
no need for JS to have a hover effect on an image. You can do that purely with CSS by adding :hover to its class/id.

Image Zoom not displayed

sorry for my English..
I to try this javascript code from w3schools.
The difference output between mine and them is that I want my result display on the same window.
How have the code;
Top above;
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.3/css/bootstrap.min.css" rel="stylesheet"/>
<link href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.13.0/css/all.min.css" rel="stylesheet"/>
<link href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet" integrity="sha384-wvfXpqpZZVQGK6TAh5PVlGOfQNHSoD2xbE+QkPxCAFlNEevoEH3Sl0sibVcOQVnN" crossorigin="anonymous">
<script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.3/js/bootstrap.min.js"> </script>
<link href="https://fonts.googleapis.com/css?family=Roboto" rel="stylesheet">
In Style,
* {box-sizing: border-box;}
.grosse-bild {
position: relative;
}
.img-zoom-lens {
position: absolute;
border: 1px solid #d4d4d4;
/*set the size of the lens:*/
width: 40px;
height: 40px;
}
.grosse-bild .kleine-fenster {
border: 1px solid #d4d4d4;
/*set the size of the result div:*/
width: 300px;
height: 300px;
}
.grosse-bild { padding: 40px; background-color: #dedee0; width: 53.7%; }
.kleine-fenster{
width: 50%;
border: none;
padding-top: 5px;
display: block;
margin-left: auto;
margin-right: auto;
}
The Javascript code,
<script>
// Initiate zoom effect:
imageZoom("myresult", "myimage");
</script>
and
function imageZoom(resultID, imgID) {
var img, lens, result, cx, cy;
img = document.getElementById(imgID);
result = document.getElementById(resultID);
/*create lens:*/
lens = document.createElement("DIV");
lens.setAttribute("class", "img-zoom-lens");
/*insert lens:*/
img.parentElement.insertBefore(lens, img);
/*calculate the ratio between result DIV and lens:*/
cx = result.offsetWidth / lens.offsetWidth;
cy = result.offsetHeight / lens.offsetHeight;
/*set background properties for the result DIV:*/
result.style.backgroundImage = "url('" + img.src + "')";
result.style.backgroundSize = (img.width * cx) + "px " + (img.height * cy) + "px";
/*execute a function when someone moves the cursor over the image, or the lens:*/
lens.addEventListener("mousemove", moveLens);
img.addEventListener("mousemove", moveLens);
/*and also for touch screens:*/
lens.addEventListener("touchmove", moveLens);
img.addEventListener("touchmove", moveLens);
function moveLens(e) {
var pos, x, y;
/*prevent any other actions that may occur when moving over the image:*/
e.preventDefault();
/*get the cursor's x and y positions:*/
pos = getCursorPos(e);
/*calculate the position of the lens:*/
x = pos.x - (lens.offsetWidth / 2);
y = pos.y - (lens.offsetHeight / 2);
/*prevent the lens from being positioned outside the image:*/
if (x > img.width - lens.offsetWidth) {x = img.width - lens.offsetWidth;}
if (x < 0) {x = 0;}
if (y > img.height - lens.offsetHeight) {y = img.height - lens.offsetHeight;}
if (y < 0) {y = 0;}
/*set the position of the lens:*/
lens.style.left = x + "px";
lens.style.top = y + "px";
/*display what the lens "sees":*/
result.style.backgroundPosition = "-" + (x * cx) + "px -" + (y * cy) + "px";
}
function getCursorPos(e) {
var a, x = 0, y = 0;
e = e || window.event;
/*get the x and y positions of the image:*/
a = img.getBoundingClientRect();
/*calculate the cursor's x and y coordinates, relative to the image:*/
x = e.pageX - a.left;
y = e.pageY - a.top;
/*consider any page scrolling:*/
x = x - window.pageXOffset;
y = y - window.pageYOffset;
return {x : x, y : y};
}
}
The Html Code,
<div class="container">
<div class="grosse-bild">
<div class="kleine-fenster" id="myresult" >
<img src="/kalamulur/Taschen-&-Rucksäcke/Rucksäcke/fenster/photo/113.jpg" width=280 height=280 class="window" id="myimage">
</div>
</div>
</div>
Here to show it..
That problem of this code is that it does nothing...
Can please someone help and say to me where is my mistake?

How to center the whole image comparison slider

When I manage to move the image comparison slider, the actual 'slider' left behind. The slider JS code is from https://www.w3schools.com/howto/howto_js_image_comparison.asp
and can be easily inspect there but I will paste the code in here too.
I have tried to move the slider with Css grid but the as mentioned before the slider icon won't move with the images.
function initComparisons() {
var x, i;
/* Find all elements with an "overlay" class: */
x = document.getElementsByClassName("img-comp-overlay");
for (i = 0; i < x.length; i++) {
/* Once for each "overlay" element:
pass the "overlay" element as a parameter when executing the compareImages function: */
compareImages(x[i]);
}
function compareImages(img) {
var slider, img, clicked = 0, w, h;
/* Get the width and height of the img element */
w = img.offsetWidth;
h = img.offsetHeight;
/* Set the width of the img element to 50%: */
img.style.width = (w / 2) + "px";
/* Create slider: */
slider = document.createElement("DIV");
slider.setAttribute("class", "img-comp-slider");
/* Insert slider */
img.parentElement.insertBefore(slider, img);
/* Position the slider in the middle: */
slider.style.top = (h / 2) - (slider.offsetHeight / 2) + "px";
slider.style.left = (w / 2) - (slider.offsetWidth / 2) + "px";
/* Execute a function when the mouse button is pressed: */
slider.addEventListener("mousedown", slideReady);
/* And another function when the mouse button is released: */
window.addEventListener("mouseup", slideFinish);
/* Or touched (for touch screens: */
slider.addEventListener("touchstart", slideReady);
/* And released (for touch screens: */
window.addEventListener("touchstop", slideFinish);
function slideReady(e) {
/* Prevent any other actions that may occur when moving over the image: */
e.preventDefault();
/* The slider is now clicked and ready to move: */
clicked = 1;
/* Execute a function when the slider is moved: */
window.addEventListener("mousemove", slideMove);
window.addEventListener("touchmove", slideMove);
}
function slideFinish() {
/* The slider is no longer clicked: */
clicked = 0;
}
function slideMove(e) {
var pos;
/* If the slider is no longer clicked, exit this function: */
if (clicked == 0) return false;
/* Get the cursor's x position: */
pos = getCursorPos(e)
/* Prevent the slider from being positioned outside the image: */
if (pos < 0) pos = 0;
if (pos > w) pos = w;
/* Execute a function that will resize the overlay image according to the cursor: */
slide(pos);
}
function getCursorPos(e) {
var a, x = 0;
e = e || window.event;
/* Get the x positions of the image: */
a = img.getBoundingClientRect();
/* Calculate the cursor's x coordinate, relative to the image: */
x = e.pageX - a.left;
/* Consider any page scrolling: */
x = x - window.pageXOffset;
return x;
}
function slide(x) {
/* Resize the image: */
img.style.width = x + "px";
/* Position the slider: */
slider.style.left = img.offsetWidth - (slider.offsetWidth / 2) + "px";
}
}
}
initComparisons();
.img-comp-container {
margin:auto;
position: relative;
height: 100vh;
width: 100vw
}
.img-comp-img {
position: absolute;
width: auto;
height: auto;
overflow:hidden;
}
.img-comp-img img {
display: block;
vertical-align: middle;
}
.img-comp-slider {
position: absolute;
z-index: 9;
cursor: ew-resize;
width: 0;
height: 0;
border-style: solid;
border-width: 9px 0 9px 14px;
border-color: transparent transparent transparent #ffffff;
}
<div class="img-comp-container">
<div class="img-comp-img">
<img src="img/ysl_before.jpg" width="650" height="450">
</div>
<div class="img-comp-img img-comp-overlay">
<img src="img/ysl_after.jpg" width="650" height="450">
</div>
</div>

I believe this fixes what you are looking for:
Wrap the existing container in another div (img-comp-outer-container), remove margin from img-comp-container and set height/width of img-comp-container to auto.
You can then style the outer container to align the component how you like
<div class="img-comp-outer-container"> <!--new div -->
<div class="img-comp-container">
<div class="img-comp-img">
<img src="img_snow.jpg" width="650" height="450">
</div>
<div class="img-comp-img img-comp-overlay">
<img src="img_forest.jpg" width="650" height="450">
</div>
</div>
</div> <!--new div end -->
.img-comp-outer-container {
/* add your styles to move around component */
}
.img-comp-container {
/* margin: auto; */
position: relative;
height: auto; /* was 100vh */
width: auto; /* was 100vw */
}

I wanted to bring the two images, that I'm comparing using image compare slider to the center of the page. The code available on W3Schools to compare images using slider but there was not suggestion about centering it. So what I did was I placed div id box and added all other classes into it and styled the box as white with height and width and added float-right to the img-comp-container. You can change the width and height of box accordingly to center the slider.
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style>
* {box-sizing: border-box;}
.img-comp-container {
float: right; /*new change*/
position: relative;
height: 200px; /*should be the same height as the images*/
}
.img-comp-img {
position: absolute;
width: auto;
height: auto;
overflow:hidden;
}
.img-comp-img img {
display:block;
vertical-align:middle;
}
.img-comp-slider {
position: absolute;
z-index:9;
cursor: ew-resize;
/*set the appearance of the slider:*/
width: 40px;
height: 40px;
background-color: #2196F3;
opacity: 0.7;
border-radius: 50%;
}
/*new change*/
#box{
background: white;
width: 150px;
height: 200px;
}
</style>
<script>
function initComparisons() {
var x, i;
/*find all elements with an "overlay" class:*/
x = document.getElementsByClassName("img-comp-overlay");
for (i = 0; i < x.length; i++) {
/*once for each "overlay" element:
pass the "overlay" element as a parameter when executing the compareImages function:*/
compareImages(x[i]);
}
function compareImages(img) {
var slider, img, clicked = 0, w, h;
/*get the width and height of the img element*/
w = img.offsetWidth;
h = img.offsetHeight;
/*set the width of the img element to 50%:*/
img.style.width = (w / 2) + "px";
/*create slider:*/
slider = document.createElement("DIV");
slider.setAttribute("class", "img-comp-slider");
/*insert slider*/
img.parentElement.insertBefore(slider, img);
/*position the slider in the middle:*/
slider.style.top = (h / 2) - (slider.offsetHeight / 2) + "px";
slider.style.left = (w / 2) - (slider.offsetWidth / 2) + "px";
/*execute a function when the mouse button is pressed:*/
slider.addEventListener("mousedown", slideReady);
/*and another function when the mouse button is released:*/
window.addEventListener("mouseup", slideFinish);
/*or touched (for touch screens:*/
slider.addEventListener("touchstart", slideReady);
/*and released (for touch screens:*/
window.addEventListener("touchend", slideFinish);
function slideReady(e) {
/*prevent any other actions that may occur when moving over the image:*/
e.preventDefault();
/*the slider is now clicked and ready to move:*/
clicked = 1;
/*execute a function when the slider is moved:*/
window.addEventListener("mousemove", slideMove);
window.addEventListener("touchmove", slideMove);
}
function slideFinish() {
/*the slider is no longer clicked:*/
clicked = 0;
}
function slideMove(e) {
var pos;
/*if the slider is no longer clicked, exit this function:*/
if (clicked == 0) return false;
/*get the cursor's x position:*/
pos = getCursorPos(e)
/*prevent the slider from being positioned outside the image:*/
if (pos < 0) pos = 0;
if (pos > w) pos = w;
/*execute a function that will resize the overlay image according to the cursor:*/
slide(pos);
}
function getCursorPos(e) {
var a, x = 0;
e = e || window.event;
/*get the x positions of the image:*/
a = img.getBoundingClientRect();
/*calculate the cursor's x coordinate, relative to the image:*/
x = e.pageX - a.left;
/*consider any page scrolling:*/
x = x - window.pageXOffset;
return x;
}
function slide(x) {
/*resize the image:*/
img.style.width = x + "px";
/*position the slider:*/
slider.style.left = img.offsetWidth - (slider.offsetWidth / 2) + "px";
}
}
}
</script>
</head>
<body>
<h1>Compare Two Images</h1>
<p>Click and slide the blue slider to compare two images:</p>
<div id="box">/*new change*/
<div class="img-comp-container">
<div class="img-comp-img">
<img src="img_snow.jpg" width="300" height="200">
</div>
<div class="img-comp-img img-comp-overlay">
<img src="img_forest.jpg" width="300" height="200">
</div>
</div>
</div>
<script>
/*Execute a function that will execute an image compare function for each element with the img-comp-overlay class:*/
initComparisons();
</script>
</body>
</html>

Amending image zoom logic

I want to set lens on preview Pane and show perfect image into zoomer div but unable to fix it. I just convert my code from some javascript example and I'm poor in javascript thats why i need help from some experts!
my expectation like image below:
my current development like:
$(function(){
$('.previewPane, #zoomer').css('background-image','url('+$('.imgkey').first().attr('src')+')');
$('.imgkey').click(function(){
$('.previewPane').css('background-image','url('+$(this).attr('src')+')');
});
$('.previewPane').mousemove(function(ev){
$('#zoomer').css('display','inline-block');
var img = $(this).css('background-image').replace(/^url\(['"](.+)['"]\)/, '$1');
var posX = ev.offsetX ? (ev.offsetX) : ev.pageX - $(this).offset().left;
var posY = ev.offsetY ? (ev.offsetY) : ev.pageY - $(this).offset().top;
$('#zoomer').css('background-position',((-posX * 3) + "px " + (-posY * 3) + "px"));
$('#zoomer').css('background-image','url('+img+')');
});
$('.previewPane').mouseleave(function(){$('#zoomer').css('display','none');});
});
.imgkey{width:50px;height:50px;border:1px solid #ddd;}
.previewPane{display:inline-block;border:1px solid #ddd;width:250px;height:250px;cursor:crosshair;background-repeat:no-repeat;background-position:center;background-size:100% 100%}
#zoomer{display:none;background-repeat:no-repeat;border:1px solid #ddd;width:250px;height:250px;z-index:1000;}
<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
</head>
<body>
<main>
<div class="previewPane"></div><div id="zoomer"></div>
<div class="imgline">
<img class="imgkey" src="https://cdn.shopify.com/s/files/1/0622/2101/products/product-image-496137782_800x.jpg?v=1519622126">
<img class="imgkey" src="https://images-na.ssl-images-amazon.com/images/I/61IPCXn13AL._SX385_.jpg">
<img class="imgkey" src="https://http2.mlstatic.com/celular-smartphone-caterpillar-s60-negro-32-gb-D_NQ_NP_940281-MCO26572973595_122017-F.jpg">
</div>
</main>
I also try your code with simple change like : just add this two line before "$('.preview').each(function() { " but no luck.
$('.img-zoom-container').html('<div class="preview"><img class="image" src="'+$('.Key').first().attr('src')+'"></div>');
$('.Key').click(function(){
$('.img-zoom-container').html('<div class="preview"><img class="image" src="'+$(this).attr('src')+'"></div>');
});
and images out side of 'img-zoom-container' like:
<img class="Key" src="https://www.w3schools.com/howto/img_girl.jpg" width="200" height="200">
<img class="Key" src="https://placeimg.com/640/480/animals" width="200" height="200">
<img class="Key" src="https://placeimg.com/640/480/arch" width="200" height="200">

You have missed the CSS from W3Schools and your image src is not working,
See working snippet with multiple images.
$('.preview').each(function() {
var lens, cx, cy, img, result;
img = $(this).find('img.image')[0];
result = document.getElementById('result');
/*create lens:*/
lens = document.createElement("div");
lens.setAttribute("class", "img-zoom-lens");
/*insert lens:*/
img.parentElement.insertBefore(lens, img);
/*calculate the ratio between result DIV and lens:*/
cx = result.offsetWidth / lens.offsetWidth;
cy = result.offsetHeight / lens.offsetHeight;
/*set background properties for the result DIV:*/
/*execute a function when someone moves the cursor over the image, or the lens:*/
$(lens).on('mousemove touchmove', moveLens);
$(img).on('mousemove touchmove', moveLens);
function getCursorPos(e) {
var a, x = 0,
y = 0;
e = e || window.event;
/*get the x and y positions of the image:*/
a = img.getBoundingClientRect();
/*calculate the cursor's x and y coordinates, relative to the image:*/
x = e.pageX - a.left;
y = e.pageY - a.top;
/*consider any page scrolling:*/
x = x - window.pageXOffset;
y = y - window.pageYOffset;
return {
x: x,
y: y
};
}
function moveLens(e) {
var pos, x, y;
result.style.backgroundImage = "url('" + img.src + "')";
result.style.backgroundSize = (img.width * cx) + "px " + (img.height * cy) + "px";
/*prevent any other actions that may occur when moving over the image:*/
e.preventDefault();
/*get the cursor's x and y positions:*/
pos = getCursorPos(e);
/*calculate the position of the lens:*/
x = pos.x - (lens.offsetWidth / 2);
y = pos.y - (lens.offsetHeight / 2);
/*prevent the lens from being positioned outside the image:*/
if (x > img.width - lens.offsetWidth) {
x = img.width - lens.offsetWidth;
}
if (x < 0) {
x = 0;
}
if (y > img.height - lens.offsetHeight) {
y = img.height - lens.offsetHeight;
}
if (y < 0) {
y = 0;
}
/*set the position of the lens:*/
lens.style.left = x + "px";
lens.style.top = y + "px";
/*display what the lens "sees":*/
result.style.backgroundPosition = "-" + (x * cx) + "px -" + (y * cy) + "px";
console.log(result);
}
})
* {
box-sizing: border-box;
}
.img-zoom-container {
width: 100%
}
.preview {
display: inline-block;
margin: 0 10px;
position: relative;
}
.img-zoom-lens {
position: absolute;
border: 1px solid #d4d4d4;
/*set the size of the lens:*/
width: 40px;
height: 40px;
}
.img-zoom-result {
border: 1px solid #d4d4d4;
/*set the size of the result div:*/
width: 300px;
height: 300px;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script>
</script>
<h1>Image Zoom</h1>
<p>Mouse over the image:</p>
<div class="img-zoom-container">
<div class="preview"><img class="image" src="https://www.w3schools.com/howto/img_girl.jpg" width="200" height="200"></div>
<div class="preview"><img class="image" src="https://placeimg.com/640/480/animals" width="200" height="200"></div>
<div class="preview"><img class="image" src="https://placeimg.com/640/480/arch" width="200" height="200"></div>
</div>
<div class="img-zoom-result" id="result"></div>

JS Image Compare button overflow

I've been editing this JS image compare example, and everything is great. I just don't know how to change one thing.
The circle button that indicates where the user should drag the image overflows out of the container when its pulled left or right. I'm talking about this: https://prnt.sc/ja1r6g
How can I fix that and make it so that when it's pulled all the way to the right or left, it goes below the image and doesn't show the overflow?
Here's the snipped of the code:
function initComparisons() {
var x, i;
/*find all elements with an "overlay" class:*/
x = document.getElementsByClassName("img-comp-overlay");
for (i = 0; i < x.length; i++) {
/*once for each "overlay" element:
pass the "overlay" element as a parameter when executing the compareImages function:*/
compareImages(x[i]);
}
function compareImages(img) {
var slider, img, clicked = 0, w, h;
/*get the width and height of the img element*/
w = img.offsetWidth;
h = img.offsetHeight;
/*set the width of the img element to 50%:*/
img.style.width = (w / 2) + "px";
/*create slider:*/
slider = document.createElement("DIV");
slider.setAttribute("class", "img-comp-slider");
/*insert slider*/
img.parentElement.insertBefore(slider, img);
/*position the slider in the middle:*/
slider.style.top = (h / 2) - (slider.offsetHeight / 2) + "px";
slider.style.left = (w / 2) - (slider.offsetWidth / 2) + "px";
/*execute a function when the mouse button is pressed:*/
slider.addEventListener("mousedown", slideReady);
/*and another function when the mouse button is released:*/
window.addEventListener("mouseup", slideFinish);
/*or touched (for touch screens:*/
slider.addEventListener("touchstart", slideReady);
/*and released (for touch screens:*/
window.addEventListener("touchstop", slideFinish);
function slideReady(e) {
/*prevent any other actions that may occur when moving over the image:*/
e.preventDefault();
/*the slider is now clicked and ready to move:*/
clicked = 1;
/*execute a function when the slider is moved:*/
window.addEventListener("mousemove", slideMove);
window.addEventListener("touchmove", slideMove);
}
function slideFinish() {
/*the slider is no longer clicked:*/
clicked = 0;
}
function slideMove(e) {
var pos;
/*if the slider is no longer clicked, exit this function:*/
if (clicked == 0) return false;
/*get the cursor's x position:*/
pos = getCursorPos(e)
/*prevent the slider from being positioned outside the image:*/
if (pos < 0) pos = 0;
if (pos > w) pos = w;
/*execute a function that will resize the overlay image according to the cursor:*/
slide(pos);
}
function getCursorPos(e) {
var a, x = 0;
e = e || window.event;
/*get the x positions of the image:*/
a = img.getBoundingClientRect();
/*calculate the cursor's x coordinate, relative to the image:*/
x = e.pageX - a.left;
/*consider any page scrolling:*/
x = x - window.pageXOffset;
return x;
}
function slide(x) {
/*resize the image:*/
img.style.width = x + "px";
/*position the slider:*/
slider.style.left = img.offsetWidth - (slider.offsetWidth / 2) + "px";
}
}
}
initComparisons();
* {box-sizing: border-box;}
.img-comp-container {
position: relative;
height: 200px; /*should be the same height as the images*/
}
.img-comp-img {
position: absolute;
width: auto;
height: auto;
overflow:hidden;
}
.img-comp-img img {
display:block;
vertical-align:middle;
}
.img-comp-slider {
position: absolute;
z-index:9;
cursor: ew-resize;
/*set the appearance of the slider:*/
width: 40px;
height: 40px;
background-color: #2196F3;
opacity: 0.7;
border-radius: 50%;
}
<h1>Compare Two Images</h1>
<p>Click and slide the blue slider to compare two images:</p>
<div class="img-comp-container">
<div class="img-comp-img">
<img src="https://placeimg.com/640/480/animals" width="300" height="200">
</div>
<div class="img-comp-img img-comp-overlay">
<img src="https://placeimg.com/640/480/animals?t=1524676145713" width="300" height="200">
</div>
</div>
EDIT: If I just add another div to wrap it all in and add overflow: hidden, it doesn't actually DO anything.

So I've got a solution. Pretty simple one. But you must know the width of your .img-comp-container. And of course overflow: hidden; is there as well
The problem is, that overflow: hidden; works as it should. But since your .img-comp-container is a block style element it spans the whole width of your webpage (or its parent container). Therefore to enforce the overflow not just vertically but also horizontally, you have to limit the width of that div to "hide" it properly
function initComparisons() {
var x, i;
/*find all elements with an "overlay" class:*/
x = document.getElementsByClassName("img-comp-overlay");
for (i = 0; i < x.length; i++) {
/*once for each "overlay" element:
pass the "overlay" element as a parameter when executing the compareImages function:*/
compareImages(x[i]);
}
function compareImages(img) {
var slider, img, clicked = 0,
w, h;
/*get the width and height of the img element*/
w = img.offsetWidth;
h = img.offsetHeight;
/*set the width of the img element to 50%:*/
img.style.width = (w / 2) + "px";
/*create slider:*/
slider = document.createElement("DIV");
slider.setAttribute("class", "img-comp-slider");
/*insert slider*/
img.parentElement.insertBefore(slider, img);
/*position the slider in the middle:*/
slider.style.top = (h / 2) - (slider.offsetHeight / 2) + "px";
slider.style.left = (w / 2) - (slider.offsetWidth / 2) + "px";
/*execute a function when the mouse button is pressed:*/
slider.addEventListener("mousedown", slideReady);
/*and another function when the mouse button is released:*/
window.addEventListener("mouseup", slideFinish);
/*or touched (for touch screens:*/
slider.addEventListener("touchstart", slideReady);
/*and released (for touch screens:*/
window.addEventListener("touchstop", slideFinish);
function slideReady(e) {
/*prevent any other actions that may occur when moving over the image:*/
e.preventDefault();
/*the slider is now clicked and ready to move:*/
clicked = 1;
/*execute a function when the slider is moved:*/
window.addEventListener("mousemove", slideMove);
window.addEventListener("touchmove", slideMove);
}
function slideFinish() {
/*the slider is no longer clicked:*/
clicked = 0;
}
function slideMove(e) {
var pos;
/*if the slider is no longer clicked, exit this function:*/
if (clicked == 0) return false;
/*get the cursor's x position:*/
pos = getCursorPos(e)
/*prevent the slider from being positioned outside the image:*/
if (pos < 0) pos = 0;
if (pos > w) pos = w;
/*execute a function that will resize the overlay image according to the cursor:*/
slide(pos);
}
function getCursorPos(e) {
var a, x = 0;
e = e || window.event;
/*get the x positions of the image:*/
a = img.getBoundingClientRect();
/*calculate the cursor's x coordinate, relative to the image:*/
x = e.pageX - a.left;
/*consider any page scrolling:*/
x = x - window.pageXOffset;
return x;
}
function slide(x) {
/*resize the image:*/
img.style.width = x + "px";
/*position the slider:*/
slider.style.left = img.offsetWidth - (slider.offsetWidth / 2) + "px";
}
}
}
initComparisons();
* {
box-sizing: border-box;
}
.img-comp-container {
position: relative;
height: 200px;
/*should be the same height as the images*/
/* Overflow must be here, and helping it up with width */
width: 300px;
overflow: hidden;
}
.img-comp-img {
position: absolute;
width: auto;
height: auto;
overflow: hidden;
}
.img-comp-img img {
display: block;
vertical-align: middle;
}
.img-comp-slider {
position: absolute;
z-index: 9;
cursor: ew-resize;
/*set the appearance of the slider:*/
width: 40px;
height: 40px;
background-color: #2196F3;
opacity: 0.7;
border-radius: 50%;
}
<h1>Compare Two Images</h1>
<p>Click and slide the blue slider to compare two images:</p>
<div class="img-comp-container">
<div class="img-comp-img">
<img src="https://placeimg.com/640/480/animals" width="300" height="200">
</div>
<div class="img-comp-img img-comp-overlay">
<img src="https://placeimg.com/640/480/animals?t=1524676145713" width="300" height="200">
</div>
</div>