"Hatena Bookmark Count Favicon" userscript

hatena-bookmark-count-favicon.user.js

// ==UserScript==
// @name Hatena Bookmark Count Favicon
// @namespace http://motemen.github.io/
// @match http://b.hatena.ne.jp/entry/*
// @match http://api.b.st-hatena.com/*
// ==/UserScript==

(function () {
    var style = window.getComputedStyle(document.querySelector('ul.entry-data li.category a'));

    function renderCount (count) {
        var SIZE = 32;

        var canvas = document.createElement('canvas');
        canvas.setAttribute('width', SIZE);
        canvas.setAttribute('height', SIZE);

        var context = canvas.getContext('2d');
        context.font = (SIZE / Math.sqrt(count.toString().length + 1)) + 'px Helvetica, sans-serif';
        context.textAlign = 'center';
        context.textBaseline = 'middle';
        context.fillStyle = style.backgroundColor;
        context.fillRect(0, 0, SIZE, SIZE);
        context.fillStyle = style.color;
        context.fillText(count.toString(), SIZE / 2, SIZE / 2);

        var previousIcons = document.querySelectorAll('link[rel$=icon]');
        for (var i = 0; i < previousIcons.length; i++) {
            previousIcons[i].parentNode.removeChild(previousIcons[i]);
        }

        var link = document.createElement('link');
        link.setAttribute('type', 'image/x-icon');
        link.setAttribute('rel', 'icon');
        link.setAttribute('href', canvas.toDataURL('image/png'));
        document.querySelector('head').appendChild(link);
    }

    var count = document.querySelector('ul.users span').innerText;
    renderCount(count)

    if (location.hash.match(/\bautoupdate(?:=(\d+))?\b/)) {
        var interval = parseInt(RegExp.$1) || 10;
        var url = document.querySelector('#head-entry-link').href;

        setInterval(function () {
            GM_xmlhttpRequest({
                method: 'GET',
                url: 'http://api.b.st-hatena.com/entry.count?url=' + encodeURIComponent(url),
                onload: function (res) {
                    renderCount(res.responseText);
                }
            })
        }, interval * 60 * 1000);
    }
})();