Post photo to facebook page using javascript and graph api
<form enctype="multipart/form-data" method="post"  action="https://graph.facebook.com/<page_id>/feed" target="ifram_name">
      <input name="source" type="file" style="font-size:13px;" />
      <input type="hidden" name="to" value="113342002047830"/>
      <input type="hidden" name="access_token" value="user_accesstoken"/>
      <input type="hidden" name="type" value="photo" />
</form>

<form action="https://graph.facebook.com/PAGE_ID/photos"
      method="post" enctype="multipart/form-data">
  <input name="source" type="file">
  <input type="hidden" name="to" value="113342002047830"/>
  <input type="hidden" name="access_token" value="user_accesstoken"/>
</form>

{
   "id": "1001207389476"
}

FB.api('/PAGE_ID/photos', 'post', {
  url: 'http://example.com/image.png',
  message: 'Upload demo'
}, function(response){
  if (response && response.id)
    console.log('Photo uploaded', response.id);
});