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javascript to change image source when hover over button

Javascript noob here. I've looked for related questions but all the results won't work for me or I don't really understand parts of them. So I might just have done a silly mistake here.
What I'm trying to do is a script that when I hover over a button, changes the source of an image.
HTML:
<button onmouseover="changeImg()" class="about" href="#">ABOUT</button>
<img class="image2" src="images/image2.png">
Javascript:
<script>
function changeImg()
{
var image = document.getElementsByClassName("image2");
image.src = "images/image1.png"
}
</script>
Is there maybe an easier way to do it? I prefer using only html css and javascript.
Thanks for the help!

You’re using getElementsByClassName which will return an array of all the elements with that class. Either use document.getElementByClassName or document.querySelector(“element”)
function changeImg() {
var image = document.getElementByClassName("image2");
image.src = "images/image1.png"
}
Another solution is to use an event listener with the e variable:
document.querySelector(“.about”).addEventListener(“mouseover”, function (e) {
e.target.src = “newSource”
})
The e.target is the image element

Javascript: Using onmouseover and onmouseout functions on more than one image

Edit: Sorry if I reply late to any solutions because I need time to figure out how they work haha
I am a beginner in Javascript and I am currently trying to use this piece of code to change an image on mouseover
// Mouseover change (Ciel):
function rollover(my_image){
my_image.src = "images/ci2_a.png";
}
function mouseaway(my_image){
my_image.src = "images/ci_a.png";
}
and this is the corresponding HTML
<img src="images/ci_a.png" onmouseover="rollover(this)" onmouseout="mouseaway(this)" alt="xxx" style="float:left; width:38%">
This works fine, but I want to do it for more than one image on the same page (a different image rollover for each picture) . Even after changing the name of the functions and stuff it doesn't work. The first image stops changing onmouseover immediately when I try to add a similar function for the next image. Could someone tell me how to perform similar events on more than one image (not concurrently)? Thank you!

You could add event listeners to all the image elements you'd like.
<img class="my-image" src="images/ci_a.png" onmouseover="rollover(this)" onmouseout="mouseaway(this)" alt="xxx" style="float:left; width:38%"/>
function rollover(){
this.src = "images/ci2_a.png";
}
function mouseaway(){
this.src = "images/ci_a.png";
}
const myImages = document.querySelectorAll('.my-image')
myImages.forEach(img => {
img.addEventListener('mouseenter', rollover)
img.addEventListener('mouseleave', mouseaway)
})

You can send the image file as the second parameter like this:
function rollover(element, image) {
element.src = image
}
...
<img onmouseover="rollover(this, 'images/ci2_a.png')" ...>
But my question is why do you need JavaScript for that? You can use a simple CSS to achieve this.

Since you need different images on load and on hover, you need a single way to define this functionality across a collection of images.
Building on Matthew's approach, here's a way to do that.
JSFiddle to test it real-time.
You'll dynamically generate the images using data attributes to store the alternate (hover) image URL.
<img class="pics" src="https://picsum.photos/id/0/100"
data-swap="https://picsum.photos/id/10/100">
<br>
<img class="pics" src="https://picsum.photos/id/1/100"
data-swap="https://picsum.photos/id/11/100">
<br>
<img class="pics" src="https://picsum.photos/id/2/100"
data-swap="https://picsum.photos/id/12/100">
<br>
<img class="pics" src="https://picsum.photos/id/3/100"
data-swap="https://picsum.photos/id/14/100">
Then define the event listeners for all elements with the class pics. Here's a list of all the events that can be referenced.
On mouseover, store the original image in a data element original.
Then change the src with the value of the data-swap.
On mouseout, replace the src with the original value.
const myImages = document.querySelectorAll('.pics')
myImages.forEach(img => {
img.addEventListener('mouseover', function () {
img.dataset.original = img.src;
img.src = img.dataset.swap;
});
img.addEventListener('mouseout', function () {
img.src = img.dataset.original;
});
})

Javascript, after eventhandler back to default (DOM)

Hello sorry for maybe a stupid question but i can't seem to find a easy solution.
The meaning of my exercise is to put 3 thumbnails on my website, but when I move over the images they need to expand in size (so i have a thumbnail version of the picture and the normal size). The normal size picture has to be on the
<p id="groot"></p>
This do work correctly, the only problem is that the pictures keep showing up when i move over it. So when I move out of the thumbnail the picture need to dissapear. Is there a function or something that get the site to the original state or any solution? Thanks in advance. I hope I explained it clearly.
This is my first question on stackoverflow, so if you have tips for a complete noob :)
This is the body of my HTML code:
<body>
<p><img id="foto1" src="images/thumb-bones.jpg" alt="bones"/>
<img src="images/thumb-castle.jpg" alt="castle"/>
<img src="images/thumb-mentalist.jpg" alt="mentalist"/>
</p>
<p id="groot"></p>
</body>
This is the JS code:
addEventListener("load", init, false);
function init() {
let foto1 = document.getElementsByTagName("img")[0].addEventListener("mouseover", actie, false);
let foto2 = document.getElementsByTagName("img")[1].addEventListener("mouseover", actie2, false);
let foto3 = document.getElementsByTagName("img")[2].addEventListener("mouseover", actie3, false);
foto1.addEventListener("click", uit, false);
}
function actie(event) {
let plaats = document.getElementById("groot");
let element = document.createElement("img");
element.src = 'images/image-bones.jpg';
plaats.appendChild(element);
}
function actie2(event) {
let plaats = document.getElementById("groot");
let element = document.createElement("img");
element.src = 'images/image-castle.jpg';
plaats.appendChild(element);
}
function actie3(event) {
let plaats = document.getElementById("groot");
let element = document.createElement("img");
element.src = 'images/image-mentalist.jpg';
plaats.appendChild(element);
}

Use a mouseout handler and, in the handler, remove all children from that element. An easy way to do that is to assign "" to innerHTML. So for instance:
function actie_off(event) {
document.getElementById("groot").innerHTML = "";
}
Hook that up to all three thumbnails.
If you don't want to use innerHTML, this question's answers give alternatives.
You might consider mouseenter and mouseleave instead of mouseover and mouseout. Probably doesn't make much difference here, it's just that mouseover repeats as the mouse moves across the thumbnails, and the bubbling of mouseout can be confusing with nested elements (not currently relevant for you). See the links for details.
Another thing to consider is to store the fullsize image URL on the thumbnail img elements as a data-* URI, like this:
<img id="foto1" src="images/thumb-bones.jpg" alt="bones" data-fullsize="images/image-bones.jpg"/>
Then you can use a single handler for all of your img elements instead of three separate ones:
function actie(event) {
let plaats = document.getElementById("groot");
let element = document.createElement("img");
element.src = this.getAttribute("data-fullsize"); // Getting the fullsize URL
// from the image the event
// relates to
plaats.appendChild(element);
}

How to make the image appear front/back on click using angular1?

I would like to implement in such a way that , when we click the image ,the selected image should appear front and the rest of the images should hide behind the selected image .
I have got the code reference of similar functionality achieved using jquery .
Click on image to move to front?
please let me know how this can be done using Angular or using plain javascript?

Using plain javascript:
let images = document.getElementsByClassName('myclass');
Array.prototype.forEach.call(images, (img) => img.addEventListener('click', function() {
Array.prototype.forEach.call(images, (img) => img.style.zIndex = 0);
this.style.zIndex = 100;
}));

Why isn't the img src/picture changing after click?

I am trying to perform a transition state from Transition State 1 to Transition State 2
The technology I am using to accomplish this JavaScript because JavaScript can dynamically "change the content of HTML elements" - JavaScript
Here is JFiddle
I saw that to change the src of an image tag in html, you have to execute this line of code (From Change Img Src)
document.getElementById("imageid").src="../template/save.png";
Here is my entire JavaScript code for the changing image portion(from my JFiddle)
(function() {
alert("got here");
function pageLoad() {
document.getElementById("choice1").onclick = getPicture("http://i.imgur.com/e95oMVZ.jpg");
document.getElementById("choice2").onclick = getPicture("http://imgur.com/dOlZ19H");
}
function getPicture(imageUrl) {
document.getElementById("picture").src = imageUrl;
}
window.onload = pageLoad;
})();
I made sure I was follow conventions for JavaScript Arguments, checked over my ids, and coded an alert statement to make sure the JavaScript was being executed.
After all of that, when I click on choice2, the image still doesn't change... Does anyone know what the issue could be?

You need to set onclick to a function. You're calling the function immediately, not when the element is clicked.
function pageLoad() {
document.getElementById("choice1").onclick = function() {
getPicture("http://i.imgur.com/e95oMVZ.jpg");
};
document.getElementById("choice2").onclick = function() {
getPicture("http://imgur.com/dOlZ19H");
};
}