JSFiddle - React, Tailwind, and code Playground

HTML

<a href="#">
    <img 
        class="swap" 
        src="http://b2evolution.net/media/blogs/man/image-rollover/image_roll_over_1.jpg?mtime=1406868196" 
        data-swap="http://b2evolution.net/media/blogs/man/image-rollover/image_roll_over_2.jpg?mtime=1406868196"
        alt="" />
</a>

JavaScript

$(function(){
   $('.swap').on('mouseenter mouseout', function(){
       var original = $(this).attr('src');
       var replacement = $(this).data('swap');
       $(this).attr('src', replacement).data('swap', original);
   });
});