Javascript to load a larger image where necessary

Responsive Enhance

This script will check whether an image is larger than a specified width and load a full resolution image if necessary.

<img id="demo" src="" alt="Responsive Image" data-fullsrc="">
<script>responsiveEnhance(document.getElementById('demo'), 400);</script>

This will replace the image with the image defined in the data-fullsrc when the image is wider than 400 pixels.