Facebook Share button: is it officially dead?

Update: As of May 2020, the Facebook documentation doesn't explicitly mention support for /sharer.php URLs, but the snippets generated by Share Button page still refer to that path.


Some time has past since this first was asked but some new information from the Facebook documentation has given us the possibility to see some official "proof" that the sharer.php method of sharing links still works, is still supported and is alive and kicking.

The reference is this page of the documentation and a few examples are also given:

This is what the simplest use of the share dialog looks like:

<a href="https://www.facebook.com/sharer/sharer.php?u=example.org" target="_blank">
  Share on Facebook
</a>

And also:

You can point to this URL in a new window or a popup. If you use JavaScript to pop open a new window, you can also refer to the URL of the current page being shared as location.href. That gives you code you can use on all pages:

var sharer = "https://www.facebook.com/sharer/sharer.php?u=";
window.open(sharer + location.href, 'sharer', 'width=626,height=436');

To summarize, there was indeed a period of time when the behavior of the sharer.php was unpredictable. It was widely accepted that the method had been deprecated and that it was not wise to use it. This has now officially been busted as an example usage of sharer.php was added to Facebook's documentation.


UPDATE #3 (June 2016):

It's gone again: There are no more references to the sharer.php in the documentation. Though you have the option to use the share dialog without integrating with the facebook sdk in any form. An important difference is the required app_id parameter. Here is one example from the docs:

<a id="facebook" href="https://www.facebook.com/dialog/share?app_id=145634995501895&display=popup&href=https%3A%2F%2Fdevelopers.facebook.com%2Fdocs%2F&redirect_uri=https%3A%2F%2Fdevelopers.facebook.com%2Ftools%2Fexplorer" target="_blank">share me</a>

UPDATE #2:

See @Lix's answer.


UPDATE #1:

As Sean pointed out (for this credit to him) you can use the FBML version of the share button. A code snippet for the FBML version:

<!DOCTYPE html>
<html xmlns:fb="http://ogp.me/ns/fb#" lang="en" style="overflow:hidden;">
    <head prefix="og: http://ogp.me/ns# fb: http://ogp.me/ns/fb#">
        <meta charset="utf-8">
        <title>Test</title>
    </head>
    <body>
        <div id="fb-root"></div>
        <script>(function(d, s, id) {
          var js, fjs = d.getElementsByTagName(s)[0];
          if (d.getElementById(id)) return;
          js = d.createElement(s); js.id = id;
          js.src = "//connect.facebook.net/en_US/all.js#xfbml=1&appId=YOUR_APP_ID"; // appId must be valid
          fjs.parentNode.insertBefore(js, fjs);
        }(document, 'script', 'facebook-jssdk'));</script>
        <fb:share-button type="button_count" href="http://www.foobar.com">
        </fb:share-button>
    </body>
</html>

NOTE: This version of the share button (like all current social plugins by Facebook) creates a cookie with the datr parameter which is a potential threat to user privacy. You should keep this in mind if you must follow privacy policies.

A code snippet for the sharer.php version:

<a id="fb-share" style='text-decoration:none;' type="icon_link" onClick="window.open('http://www.facebook.com/sharer.php?s=100&amp;p[title]=foo&amp;p[summary]=bar&amp;p[url]=https://www.foobar.com/&amp;p[images][0]=https://www.foobar.com/thumb.gif','sharer','toolbar=0,status=0,width=580,height=325');" href="javascript: void(0)">
    <img src="img/share.gif" width="62" height="18" alt="Share"/>
</a>



ORIGINAL ANSWER:

The Share Button has been deprecated already a while ago. It might be dead completely now, or just temporarily, only Facebook knows. Officially it is deprecated.

From the documentation:

What happened to the old Share button?

We deprecated the Share Button when we launched the Like button [...]