JavaScript: Invert color on all elements of a page

My solution seems to work only for Chrome right now, but it inverts everything (including images and iframes) as seen here:

Also it does not make use of external libraries and is very simple: adding a -webkit-filter: invert(100%) to the html-selector.

javascript: (
function () { 
// the css we are going to inject
var css = 'html {-webkit-filter: invert(100%);' +
    '-moz-filter: invert(100%);' + 
    '-o-filter: invert(100%);' + 
    '-ms-filter: invert(100%); }',

head = document.getElementsByTagName('head')[0],
style = document.createElement('style');

// a hack, so you can "invert back" clicking the bookmarklet again
if (!window.counter) { window.counter = 1;} else  { window.counter ++;
if (window.counter % 2 == 0) { var css ='html {-webkit-filter: invert(0%); -moz-filter:    invert(0%); -o-filter: invert(0%); -ms-filter: invert(0%); }'}
 };

style.type = 'text/css';
if (style.styleSheet){
style.styleSheet.cssText = css;
} else {
style.appendChild(document.createTextNode(css));
}

//injecting the css to the head
head.appendChild(style);
}());

Here's the fiddle: http://jsfiddle.net/nikita_turing/jVKw6/3/ with the bookmarklet included. If someone has an idea of how to make it work for Firefox (SVG-Filters?), go ahead!

I cleaned up the comments from one of the answers (by leosok) above, so it will work as a bookmarklet in chrome. Note that this solution is more efficient than the current highest-point here, plus it works even if the html changes after you run the script.

javascript:(function () { 
    var css = 'html {-webkit-filter: invert(100%);' + '-moz-filter: invert(100%);' + '-o-filter: invert(100%);' + '-ms-filter: invert(100%); }';
    var head = document.getElementsByTagName('head')[0];
    var style = document.createElement('style');
    if (!window.counter) { 
        window.counter = 1;
    } else { 
        window.counter++;
        if (window.counter % 2 == 0) { 
            var css = 'html {-webkit-filter: invert(0%); -moz-filter: invert(0%); -o-filter: invert(0%); -ms-filter: invert(0%); }'
        } 
    }
    style.type = 'text/css';
    if (style.styleSheet) {
        style.styleSheet.cssText = css;
    } else {
        style.appendChild(document.createTextNode(css));
    }
    head.appendChild(style);
}());

One line for bookmarklet. create a bookmark, then edit the url to this: javascript:(function () { var css = 'html {-webkit-filter: invert(100%);' + '-moz-filter: invert(100%);' + '-o-filter: invert(100%);' + '-ms-filter: invert(100%); }'; var head = document.getElementsByTagName('head')[0]; var style = document.createElement('style'); if (!window.counter) { window.counter = 1; } else { window.counter++; if (window.counter % 2 == 0) { var css = 'html {-webkit-filter: invert(0%); -moz-filter: invert(0%); -o-filter: invert(0%); -ms-filter: invert(0%); }' } } style.type = 'text/css'; if (style.styleSheet) { style.styleSheet.cssText = css; } else { style.appendChild(document.createTextNode(css)); } head.appendChild(style); }());

First things first, grab the awesome RGBColor class here.

Here goes:

jsFiddle example

//set up color properties to iterate through
var colorProperties = ['color', 'background-color'];

//iterate through every element in reverse order...
$("*").get().reverse().each(function() {
    var color = null;

    for (var prop in colorProperties) {
        prop = colorProperties[prop];

        //if we can't find this property or it's null, continue
        if (!$(this).css(prop)) continue; 

        //create RGBColor object
        color = new RGBColor($(this).css(prop));

        if (color.ok) { 
            //good to go, let's build up this RGB baby!
            //subtract each color component from 255
            $(this).css(prop, 'rgb(' + (255 - color.r) + ', ' + (255 - color.g) + ', ' + (255 - color.b) + ')');
        }
        color = null; //some cleanup
    }
});

Screenshot:

EDIT: Here's a bookmarklet you can now copy-paste into your browser (http://jsfiddle.net/F7HqS/1/)

javascript:function load_script(src,callback){var s=document.createElement('script');s.src=src;s.onload=callback;document.getElementsByTagName('head')[0].appendChild(s);}function invertColors(){var colorProperties=['color','background-color'];$('*').each(function(){var color=null;for(var prop in colorProperties){prop=colorProperties[prop];if(!$(this).css(prop))continue;color=new RGBColor($(this).css(prop));if(color.ok){$(this).css(prop,'rgb('+(255-color.r)+','+(255-color.g)+','+(255-color.b)+')');}color=null;}});}load_script('http://www.phpied.com/files/rgbcolor/rgbcolor.js',function(){if(!window.jQuery)load_script('https://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js',invertColors);else invertColors();});

The accepted answer is totally correct, with one minor flaw. Each time you toggle the invert it adds ANOTHER style tag to the head. Do this instead

  // the css we are going to inject
  let css = 'html {-webkit-filter: invert(100%);' +
    '-moz-filter: invert(100%);' +
    '-o-filter: invert(100%);' +
    '-ms-filter: invert(100%); }';

  let head = $('head')[0];
  let invertStyle = $('#invert')[0];

  if (invertStyle) {
    head.removeChild(invertStyle);
  } else {
    let style = document.createElement('style');

    style.type = 'text/css';
    style.id = 'invert';
    if (style.styleSheet){
      style.styleSheet.cssText = css;
    } else {
      style.appendChild(document.createTextNode(css));
    }

    //injecting the css to the head
    head.appendChild(style);
  }

That way you simply remove the tag if you want to undo your invert. Works great!