JSFiddle - React, Tailwind, and code Playground
HTML
<img src='http://www.google.com/intl/en_ALL/images/srpr/logo1w.png'>
<img src='http://l.yimg.com/a/i/mntl/ww/events/p.gif'>
JavaScript
var $allImages = $('img');
$allImages.each( function() {
var curUrl = $(this).attr('src');
var newUrl = '_thumbs/' + curUrl;
$(this).attr('src',newUrl);
})