I've been fiddling around with this all morning, as I'm very new to JS I'm not getting very far. I felt it would be better to start from scratch on here.
I'm wanting to switch the image when the button is on hover. The current image is: http://via.placeholder.com/350x150, and we could change to: http://via.placeholder.com/200x100
EDIT: I didn't realise you could do this in pure CSS. I will do my research, although any examples doing the css route would be appreciated.
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" rel="stylesheet"/>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.bundle.min.js" integrity="sha384-feJI7QwhOS+hwpX2zkaeJQjeiwlhOP+SdQDqhgvvo1DsjtiSQByFdThsxO669S2D" crossorigin="anonymous"></script>
<body>
<div class="container-fluid">
<div class="row">
<div class="col-md-6">
<h1>Testing image hover</h1>
<p class="mt-3">Just a test... just a test...</p>
<button class="btn btn-success btn-lg">Test button</button>
</div>
<div class="col-md-6">
<img style="display: width:100vh; height: 90vh;" src="http://via.placeholder.com/350x150">
</div>
</div>
</div>
</body>