PinterestWidgetsOnTumblr

// see http://engineering.pinterest.com/post/52094692633/how-to-make-pinterest-widgets-work-on-tumblr 
// for instructions and explanation
<script>
// be sure this script doesn't mess up anything else on this page
(function (d, att) {
  // declare some variables
  var link, pair, part, i, j, k, n, hazWidget, script;
  // find all the links on the page
  link = d.getElementsByTagName('A');
  // go through them one at a time
  for (i = 0, n = link.length; i < n; i = i + 1) {
    // do we have a rev and a class name that matches our pattern?
    if (link[i][att]) {
      // split the attribute into individual directives
      pair = link[i][att].split(' ');
      // loop through each directive
      for (j = 0, k = pair.length; j < k; j = j + 1) {
        // split into parts: first is key, second is value
        part = pair[j].split('=');
        // do we have two parts?
        if (part[0] && part[1]) {
          // set the attribute on the link
          link[i].setAttribute(part[0], part[1]);
          // after this is all done, build a widget
          if (part[0] === 'data-pin-do') {
            hazWidget = true;
          }
        }
      }
    }
  }
  // do we need to build a widget?
  if (hazWidget === true) {
    // make a script
    script = d.createElement('SCRIPT');
    // set the type
    script.setAttribute('type', 'text/javascript');
    // set the character set
    script.setAttribute('charset', 'utf-8');
    // set the source
    script.setAttribute('src', '//assets.pinterest.com/js/pinit.js');
    // carefully append it to the body
    d.getElementsByTagName('BODY')[0].appendChild(script);
  }
// if you would like to use some other attribute instead of rev, change it here
}(document, 'rev'));
</script>