WordPress 3.5 media uploader in easier steps. If using other than edit post screen, don't forget to use wp_enqueue_media(); in your functions.php

WP3.5 Media Uploader

jQuery(document).ready(function($){
  var _custom_media = true,
      _orig_send_attachment = wp.media.editor.send.attachment;
  $('.stag-metabox-table .button').click(function(e) {
    var send_attachment_bkp = wp.media.editor.send.attachment;
    var button = $(this);
    var id = button.attr('id').replace('_button', '');
    _custom_media = true;
    wp.media.editor.send.attachment = function(props, attachment){
      if ( _custom_media ) {
        $("#"+id).val(attachment.url);
      } else {
        return _orig_send_attachment.apply( this, [props, attachment] );
      };
    }
    wp.media.editor.open();
    return false;
  });
  $('.add_media').on('click', function(){
    _custom_media = false;
  });
});

Changing

wp.media.editor.open(button);

to

wp.media.editor.open();

helped me get rid of a document.getElementById(...) is null error.

yes!! awesome!