kokubunize aka NDKify for UserScript

kokubunizer.user.js

// ==UserScript==
// @name        kokubunizer
// @namespace   https://flavors.me/noromanba
// @description kokubunize aka NDKify for UserScript
// @include     https://www.facebook.com/*
// @downloadURL https://raw.github.com/gist/4236851/kokubunizer.user.js
// @installURL  https://raw.github.com/gist/4236851/kokubunizer.user.js
// @version     2012.12.8.3
// @license     WTFPL http://sam.zoy.org/wtfpl/ (Do What The Fuck You Want To Public License)
// @contributor udzura  https://gist.github.com/4212643
// @author      noromanba (http://flavors.me/noromanba)
// @homepage    https://gist.github.com/4236851
// @icon        https://upload.wikimedia.org/wikipedia/commons/thumb/b/ba/New_Bearnstar.png/32px-New_Bearnstar.png
// @icon64      https://upload.wikimedia.org/wikipedia/commons/thumb/b/ba/New_Bearnstar.png/64px-New_Bearnstar.png
// ==/UserScript==

// Warranty clause http://sam.zoy.org/wtfpl/
/* This program is free software. It comes without any warranty, to
 * the extent permitted by applicable law. You can redistribute it
 * and/or modify it under the terms of the Do What The Fuck You Want
 * To Public License, Version 2, as published by Sam Hocevar. See
 * http://sam.zoy.org/wtfpl/COPYING for more details. */

// Icon (Public Domain by Lawinc82)
// https://commons.wikimedia.org/wiki/File:New_Bearnstar.png

// Devel
// https://gist.github.com/4236851

// c.f. http://ptech.g.hatena.ne.jp/noromanba/20121207/1354931086
(function () {
    var slice = Array.prototype.slice;

    var debounce = function (func, threshould) {
        var timer;
        return function () {
            var context = this, args = slice.call(arguments);
            clearTimeout(timer);
            timer = setTimeout(function () {
                func.apply(context, args);
            }, threshould || 10);
        };
    };

    var kokubunize = debounce(function () {
        var hdif = '今どんな気持ち？',
            ndk = 'ねえねえ' + hdif;
        // c.f. http://ptech.g.hatena.ne.jp/noromanba/20120521/1337639496
        slice.call(document.querySelectorAll('textarea[placeholder="' + hdif +'"]')).forEach(function (area) {
                // some browser support c.f. http://help.dottoro.com/ljgugboo.php
                if (area.placeholder) {
                    area.placeholder = ndk;
                } else { // XXX redundant, if this block for polyfill, no needed to set @placeholder ...why?
                    area.setAttribute('placeholder', ndk);

                    if (area.value === hdif) {
                        area.value = ndk;
                    }
                }
        });
    }, 100);

    // TBD replace to MutationObserver
    document.addEventListener('DOMNodeInserted', function (evt) {
        kokubunize();
    }, false);
})();

// DBG with <at>include http://*
// c.f. http://www.ne.jp/asahi/nanto/moon/2010/12/28/placeholder.html
//      http://webdesignerwall.com/demo/html5-placeholder-text/
/*
        slice.call(document.querySelectorAll('input[placeholder]')).forEach(function (area) {
*/
/*/
var rapidfire = function () {
    Array.apply(null, Array(100)).forEach(function (_, idx) {
        console.info('*', _, idx);
        var input = document.createElement('input');
        input.name = idx;
        input.placeholder = idx;
        input.value = !!(idx % 2) ? idx : '';
        document.body.appendChild(input);
    });
};
//*/