Add transition while changing img src with javascr

Question

I have an img tag that I want to change the src when hover and it all works but i would like to add some transition so it doesn't look so rough but since it's an img src i cant target it with css.

http://jsfiddle.net/Ne5zw/1/

html

<img id="bg" src="img/img1.jpg">
<div onmouseover="imgChange('img/img2.jpg'); "onmouseout="imgChange('img/img1.jpg');">

js

function imgChange(im){
document.getElementById('bg').src=(im);
}

Answer 1

i usually use jquery for this.

$(document).on("mouseover", '.image_class', function () {
        $(this).attr('src', 'img/img2.jpg');
    });

$(document).on("mouseout", '.image_class', function () {
        $(this).attr('src', 'img/img1.jpg');
  });

Answer 2

You want a crossfade. Basically you need to position both images on top of each other, and set one's opacity to 0 so that it will be hidden:

<div id="container">
    <img class="hidden image1" src="http://www.istockphoto.com/file_thumbview_approve/4629609/2/istockphoto_4629609-green-field.jpg">

    <img class="image2" src="http://www.istockphoto.com/file_thumbview_approve/9958532/2/istockphoto_9958532-sun-and-clouds.jpg" />
</div>

CSS:

.hidden{
 opacity:0;   
}

img{
    position:absolute;
    opacity:1;
    transition:opacity 0.5s linear;
}

With a transition set for opacity on the images, all we need to do is trigger it with this script:

$(function(){
    debugger;
    $(document).on('mouseenter', '#hoverMe', function(){
        $('img').toggleClass('hidden');
    });
});

http://jsfiddle.net/Ne5zw/12/

Answer 3

Here is a pure css solution using css transition. You can use a div as the container and set the background-image on hover.

.image-container {
  background: url(http://placeholder.pics/svg/300x300/DEDEDE/555555/Old%20Image) center center no-repeat;
  background-size: contain;

  width: 150px;
  height: 150px;

  -webkit-transition: all .3s ease-in-out;
  -moz-transition: all .3s ease-in-out;
  transition: all .3s ease-in-out;
}

.image-container:hover {
  background-image: url("http://placeholder.pics/svg/300x300/DEDEDE/555555/New%20Image");
}

<div class="image-container"></div>

Answer 4

Just in case someone is curious how to actually create a transition-like effect when you are actually changing the source attribute of an image, this was the solution I came up with.

Javascript:

        var bool = false;
        setInterval(() => {
            bool = !bool;
            let imgSrc = bool ? 'hero-bg2.jpg' : 'hero-bg.jpg'; // Toggle image
            $('.parallax-slider').addClass('transitioning-src'); // Add class to begin transition
            setTimeout(() => {
                $('.parallax-slider').attr('src', `https://website.com/images/${imgSrc}`).removeClass('transitioning-src');
            }, 400); // Ensure timeout matches transition time, remove transition class
        }, 6000);

CSS:

.parallax-slider {
    transition: opacity 0.4s ease-in;
    -webkit-transition: opacity 0.4s ease-in;
    -moz-transition: opacity 0.4s ease-in;
    -ms-transition: opacity 0.4s ease-in;
    -o-transition: opacity 0.4s ease-in;
    opacity: 1;
}
.transitioning-src {
    transition: opacity 0.4s ease-out;
    -webkit-transition: opacity 0.4s ease-out;
    -moz-transition: opacity 0.4s ease-out;
    -ms-transition: opacity 0.4s ease-out;
    -o-transition: opacity 0.4s ease-out;
    opacity: 0;
}

This will give the illusion of 'fading to black and back' between images - even if you're using something like parallax.js where you have a data-attribute driven component that renders out into a dynamic image. Hope it helps someone.