JSFiddle - React, Tailwind, and code Playground

HTML

<img src="extension.jpg">
<img src="ext.ension.jpg">

CSS

img {
    height: 100px;
    width: 100px;
    background: red;
}

img[src*="-fx.jpg"] {
    background: blue;
}

JavaScript

$('img').each(function(){
	var a = $(this).attr('src');
    var b = a.split('.')
    var c = b[0] + '-fx' + '.' + b[1];
    console.log(c);
    $(this).attr('src', c);    
});