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How to replace an <img/> HTML tag using JavaScript .replace() method

I have a img tag like
<img src="Mesothelioma_image_1.jpg"/>
I want to replace this tag with something like
<amp-img class="blog-image" src="Mesothelioma_image_1.jpg" width="50" height= "20" layout="responsive"></amp-img>
By keeping the same src attribute value.

You can use querySelector() to find the image. It would be easier if the image contains an id attribute.
Then, use createElement() to create the dom element by name amp-img.
Use setAttribute() to assign attributes to the new elements such as class, src, width, erc.
Use insertBefore() to add new element to the page and remove() to remove the old image element.
NOTE: I am selecting the old image with its src, please change it as per your need.
var oldImage = document.querySelector('img[src="Mesothelioma_image_1.jpg"]');
var newImage = document.createElement('amp-img');
newImage.setAttribute("class","blog-image");
newImage.setAttribute("src", oldImage.getAttribute('src'));
newImage.setAttribute("width","50");
newImage.setAttribute("height","20");
newImage.setAttribute("layout","responsive");
oldImage.parentNode.insertBefore(newImage, oldImage);
oldImage.parentNode.removeChild(oldImage);
console.log(document.querySelector('amp-img[src="Mesothelioma_image_1.jpg"]')); // to find the appended new image
<img src="Mesothelioma_image_1.jpg"/>

Please see below code.
You will need to access img using parent class or Id.
i have did this work on a link click event, You can do this on document.ready or any other event as well.
jQuery('.clickMe').click(
function(e){
e.preventDefault();
var img = jQuery('.parent img').attr('src');
var newhtml='<amp-img class="blog-image" src="'+img+'" width="50" height= "20" layout="responsive"></amp-img>';
// console.log('IMG: '+ img);
jQuery('.parent').html(newhtml);
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="parent">
<img src="https://mosthdwallpapers.com/wp-content/uploads/2016/08/Pakistan-Flag-Image-Free-Download.jpg"/>
</div>
<a class="clickMe" href="#">Click Me </a>
<amp-img class="blog-image" src="Mesothelioma_image_1.jpg" width="50" height= "20" layout="responsive"></amp-img>

Why append elements not a draggable?

I make all elements with an "image" class draggable.
Then I append more "image" elements to the page.
Why aren't the appended elements draggable?
$(function() {
$('.image').draggable(); //Draggable image (Jquery UI)
$('.button').click(function() { //append more image
$('body').append('<img class="image" src="http://nuclearpixel.com/content/icons/2010-02-09_stellar_icons_from_space_from_2005/earth_128.png">')
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="//code.jquery.com/ui/1.12.0-beta.1/jquery-ui.min.js"></script>
<img class="image" src="http://nuclearpixel.com/content/icons/2010-02-09_stellar_icons_from_space_from_2005/earth_128.png">
<button class="button">Append image</button>
View on JSFiddle

You need to call .draggable(); on the newly created image on every button click.
$(function(){
$('.image').draggable(); //Draggable image (Jquery UI)
$('.button').click(function(){ //append more image
var img = $('<img class="image" src="http://nuclearpixel.com/content/icons/2010-02-09_stellar_icons_from_space_from_2005/earth_128.png">');
img.draggable();
$('body').append(img);
});
}) //End of script
fiddle: https://jsfiddle.net/0jxghvaa/2/

You're instantiating the draggable() plugin on the .image elements at load. Any elements added to the DOM after that will need the plugin instantiating on them once they are created. Try this:
$('.image').draggable();
$('.button').click(function() {
var $img = $('<img class="image" src="http://nuclearpixel.com/content/icons/2010-02-09_stellar_icons_from_space_from_2005/earth_128.png">').appendTo('body');
$img.draggable();
});

Newly added elements will not be automatically drag-able (only those elements existing initially).
Inside your function, try re-declaring that the element will be drag-able, AFTER it is created:
$('.button').click(function(){
$('body').append('<img class="image" src="http://nuclearpixel.com/content/icons/2010-02-09_stellar_icons_from_space_from_2005/earth_128.png">');
$('.image').draggable();
});

Adding an image via pure JS

I am new in JS,please help me.I have 4 images with the same class name and a hidden div which is displayed when one of 4 images is clicked. How i can add to my div the image which one is clicked? I do not want to write a function for every image.Is it possible with my code?
<img onClick="show()"class="img" src="css/images1/img1.png">
<img onClick="show()"class="img" src="css/images1/img2.png">
<img onClick="show()"class="img" src="css/images1/img3.png">
<img onClick="show()"class="img" src="css/images1/img4.png">
<div class="gallery"></div>
<script>
function show(){
var x=document.getElementsByClassName('gallery')[0];
x.style.display="block";
x.innerHTML='<img src=css/images1/img1.jpg>';
};
</script>

Pass in the "src" of the element that was clicked:
function show(src){
var x=document.getElementsByClassName('gallery')[0];
x.style.display="block";
x.innerHTML = '<img src="' + src + '">';
}
Then for your html <img/> tags pass in their src to show:
<img onClick="show(this.src)"class="img" src="css/images1/img1.png">
Edit: if you must select "gallery" by className, use getElementsByClassName as you originally had.

How to use JQuery .find() properly when using multiple divs

I have an HTML page where users can create a newsitem. Each news item is displayed in a new div, with multiple divs inside to divide content into multiple columns, to hide some content etc. The following code is a stripped down version of 1 newsitem:
<div class="news-item clearfix" id="c-b504b780-06a8-49bc-ba04-84d1fbba1a94">
<h2>This is a title</h2>
<div class="news-image div-right">
<a class="img-gallery" href="Images/Dynamic/700x700/NewsItem/44951/example.png" rel="lightbox-This is a title"><img class="img-responsive clear" src="Images/Dynamic/200x200c/NewsItem/44951/example.png" /></a><br />
</div>
<div class="preview one-image">
<p>Text here</p>
</div>
<div class="full div-hide">
<p>Text here</p> <img src="Images/Dynamic/full/NewsItem/44951/example.png" class="img-responsive" />
</div>
As you can see, each newsitem has a generated code attached to it which is used to identify unique newsitems, the code is also used in my javascript:
<script type="text/javascript">
(function () {
var newsdiv = $('#c-b504b780-06a8-49bc-ba04-84d1fbba1a94');
$('#c-b504b780-06a8-49bc-ba04-84d1fbba1a94 > .full').find('img').wrap(function () { return "<a href='" + $(this).attr('src') + "'></a>"; });
})();
</script>
This script is supposed to put an anchor tag around the image found in my full div-hide class, however this is not working properly. I assume my jquery selector is not selecting the right div, but I do not know what it should be. Do you have an idea how I can wrap my anchor tags around images inside the class="full" div?

You have two issue in document ready function:
1) You have not added jquery selector($) in front of ready function.
2) You dont need to call the document ready function.
$(function () {
/*^^missing selector here*/
var newsdiv = $('#c-b504b780-06a8-49bc-ba04-84d1fbba1a94');
$('#c-b504b780-06a8-49bc-ba04-84d1fbba1a94 > .full').find('img').wrap(function () { return "<a href='" + $(this).attr('src') + "'></a>"; });
});
/*^^ () not required here*/
and to make it work for all the divs:
$('.news-item .full img').each(function(){
$(this).wrap("<a href='" + $(this).attr('src') + "'></a>");
});
Working Demo

Try this:
$('#c-b504b780-06a8-49bc-ba04-84d1fbba1a94 > .full img').each(function() {
$(this).wrap(function () { return "<a href='" + $(this).attr('src') + "'></a>"; });
});

$('div.full').find('img').each(function() {
// your code here ..
});

Replace <img> with <object>

Here is a little challenge: I'm trying to replace all three <img ...> tags in the code below completely by another tag named <object ...>. I Tried with jQuery .replaceWith() but didn't get it.
$( document ).ready(function() {
$("div.gallery_content > div > ul > li:firstchild > img").replaceWith( "<object>...</object>" );
});
I can't change any of the classes or add any ID or class names. And I can't change the code in any way. I can just add some Javascript / jQuery in an .js file that is already attached.
What makes things even more difficult is the fact, that I have to add the Javascript to every page on the website, but the replacement should only take place on a subpage called «spots» (e.g. .com/cms/anything/spots).
This is the code:
<div class="gallery_content">
<div id="navkeys" style="visibility: hidden;"></div>
<div>
<ul style="width: 2281px; margin-left: 0px;">
<li style="margin-left: 0px;">
<img src="XYZ" width="760" height="505" alt="XYZ" style="visibility: visible;">
<div class="gallery_details">
Some Text
</div>
</li>
<li>
<img src="XYZ" width="760" height="505" alt="XYZ" style="visibility: visible;">
<div class="gallery_details">
Some Text
</div>
</li>
<li>
<img src="XYZ" width="760" height="505" alt="XYZ" style="visibility: visible;">
<div class="gallery_details">
Some Text
</div>
</li>
</ul>
</div>
</div>
Has anyone got a clue?

Once a dom element is created, the tag is immutable.
You would have to remove the image element and replace it with an object. So you would need to get all of the information you need and then add an object element.
So you could do something like this:
$("div.gallery_content > div > ul > li:firstchild > img").each(function() {
var src = $(this).attr('src');
var width = $(this).attr('width');
.
.
.
etc...
$(this).remove();
$('<object>...</object>').prependTo('li') //or whatever your selector is to prepend.
});

The other users have given the code for the replacement, but forgot to explain how the code must act to execute only in the target page
var targetPath = "com/cms/anything/spots";
$(window).load(function(){
currentPath = window.location.pathname;
//Checks if the current page coincides with the target page
if(currentPath.indexOf(targetPath)+targetPath.length === currentPath.length){
functionThatReplaces();
}
});
With this, the script will check if the page is the correct before executing the code.

You can create a new object element, with all the attributes of the old one and then replace the img tag.
JSFiddle: http://jsfiddle.net/TrueBlueAussie/z9u5dxgu/2/
$(document).ready(function () {
$("div.gallery_content > div > ul > li > img").each(function () {
// create a new object
var $object = $('<object>');
$object.html($(this).html());
// copy all the attributes
var attributes = $(this).prop("attributes");
// loop through attributes and apply them to object
$.each(attributes, function () {
$object.attr(this.name, this.value);
});
$(this).replaceWith($object);
});
});
If it were not an img you would also copy the innerHTML using .html().
The end result of the JSFiddle looks like:
<li style="margin-left: 0px;">
<object src="XYZ" width="760" height="505" alt="XYZ" style="visibility: visible;"></object>
<div class="gallery_details">Some Text</div>
</li>
The other minor detail you mentioned was matching a specific page only (difficult to test in a JSFiddle):
$(document).ready(function () {
if (window.location.href.indexOf("/cms/anything/spots") > 0){
$("div.gallery_content > div > ul > li > img").each(function () {
// create a new object
var $object = $('<object>');
$object.html($(this).html());
// copy all the attributes
var attributes = $(this).prop("attributes");
// loop through attributes and apply them to object
$.each(attributes, function () {
$object.attr(this.name, this.value);
});
$(this).replaceWith($object);
});
}
});