SCP Foundation reading helper

userscript.js

// ==UserScript==
// @name         SCP Foundation reading helper
// @namespace    http://hrnz.net/
// @version      0.1
// @description  Adds simple buttons to SCP page to allow easy paging.
// @author       Martin Thurau <martin.thurau@gmail.com>
// @match        http://www.scp-wiki.net/scp-*
// @grant        unsafeWindow
// @grant        GM_addStyle
// @grant        GM_setValue
// @grant        GM_getValue
// ==/UserScript==

GM_addStyle(".tm_button { cursor: pointer; }");

var $ = unsafeWindow.jQuery,
    title = $('#page-title'),
    next = $('<span class="tm_button">►</span>'),
    prev = $('<span class="tm_button">◄</span>'),
    lastReadPage = GM_getValue('last-read-page', null),
    lastRead = $('<span class="tm_button">☛</span>'),
    titleText = $('<span>' + title.text().trim() + '</span>');


// add elements to DOM
title.empty().append(titleText, '&nbsp;', prev);
if(lastReadPage !== null) {
    title.append(lastRead);
    updateLastRead(lastReadPage);
}
title.append(next);

// event handler
prev.click(function(e) {
	e.preventDefault();
    changePage(-1);
});

next.click(function(e) {
	e.preventDefault();
    changePage(+1);
});

lastRead.click(function(e) {
	e.preventDefault();
    loadPage(lastReadPage);
});

// change page relative
function changePage(delta) {
    var match = (/\/scp-(\d+).*/).exec(document.location.pathname);
    if (match) {
        loadPage(parseInt(match[1]) + delta);
    }
}

// load the specified page and insert into DOM
function loadPage(page) {
    var url = document.location.origin + '/scp-' + page;
    $('#page-content').load(url + ' #page-content', function() {
        titleText.text('SCP-' + page);
        history.pushState(null, "", url);
        updateLastRead(page);
    });
}

// update state and stored value
function updateLastRead(page) {
    lastReadPage = page;
    GM_setValue('last-read-page', page);
    lastRead.attr('title', 'Go to last read page: ' + page)
}