Unproxy Gmail Images

Update: A domain administrator can turn this off or set a domain whitelist in Google Apps domain settings.

Gmail last week introduced a feature that proxies all images. This is bad if you're developing emails, pointing the browser to images on your internal network: Google can't see those, and you get broken images in Gmail. Here's a JavaScript snippet that replaces image src attributes with the original image URL, which Google kindly stores in the anchor of the proxied URL:

NodeList.prototype.filter = function(callback) {
    return Array.prototype.filter.call(this, callback);
};

document.getElementsByClassName('adP').filter( function(elem) {
  elem.getElementsByTagName('img').filter( function(elem) {
    var src = elem.getAttribute('src'),
      parts = src.split('#', 2);
    if (parts[0].indexOf('googleusercontent.com/proxy/')) {
      elem.setAttribute('src', parts[1]);
    }
  })
});

Here's the same as a bookmarklet: unproxy gmail.