What are important factors when implementing second images on hover? - html

Question

I'm implementing a second image on hover in a list. This is very common for example in list views of products. I have two ideas for how to do this:
Either put two images on top of each other like this
<div class="wrapper">
<img src="1.jpg" />
<img src="2.jpg" />
<div>
Then hide one image and when hovering the wrapper I will show it with css.
Or I would make one div:
<div class="container" />
and then use inline css to set the background images on .container.
I could also do something with javascript of course.
How, if at all, would these solutions affect performance on hover and page-loading time? Is there an even better solution? The site is built in react.

Answer 1

Since you are using react, you could simply manage the visibility of that second image via the state.
But if you only have two images and don't need any kind of cycling of images, using css should be the solution with the best performance.
Use your current setup like this:
<div class="wrapper">
<img src="1.jpg" />
<img src="2.jpg" />
<div>
And put the first image ontop of the second one. Then just hide the first element on hover.
The only impact this has on performance/loading time is, that you would fetch two images per item on page load.
Using react instead, the second image would not be loaded until you render it into the DOM (But if the image takes some time to load, it wont look that smooth).
However, native css transitions are much more efficient than solving this with react. At least for this small usecase.
If you however want to solve it with react, I would suggest trying your backgroundImage approach. Just keep track of the hover state in your component and switch the background image accordingly.

Answer 2

I think, the easiest way would be:
.sample {
background: url(http://placehold.it/200?text=First) center/cover no-repeat;
height: 200px;
width: 200px;
}
.sample:hover {
background-image: url(http://placehold.it/200?text=Second);
}
<div class="sample"></div>
And with image paths inlined:
.sample {
background: url() center/cover no-repeat;
height: 200px;
width: 200px;
}
.sample:hover img {
opacity: 0;
}
<div class="sample" style="background-image: url('http://placehold.it/200?text=Second')">
<img src="http://placehold.it/200?text=First" />
</div>