setrl.userscript.js

// ==UserScript==
// @version       0.2
// @name          Stack Exchange Timeline/Revisions links
// @description   Adds timeline and revisions links to all applicable Stack Exchange posts
// @author        Jeff Mercado
// @namespace     https://stackoverflow.com/users/390278/jeff-mercado
// @include       http*://stackoverflow.com/*
// @include       http*://*.stackoverflow.com/*
// @include       http*://askubuntu.com/*
// @include       http*://*.askubuntu.com/*
// @include       http*://superuser.com/*
// @include       http*://*.superuser.com/*
// @include       http*://serverfault.com/*
// @include       http*://*.serverfault.com/*
// @include       http*://mathoverflow.net/*
// @include       http*://*.mathoverflow.net/*
// @include       http*://stackapps.com/*
// @include       http*://*.stackapps.com/*
// @include       http*://*.stackexchange.com/*
// @exclude       http*://chat.*.com/*
// ==/UserScript==

// this serves only to avoid embarassing mistakes caused by inadvertently loading this script onto a page that isn't a Stack Exchange page
let isSEsite = false;
for (let s of document.querySelectorAll('script')) isSEsite = isSEsite||/StackExchange\.ready\(/.test(s.textContent);

// don't bother running this if this isn't a scripted SE page
if (!isSEsite || typeof StackExchange === 'undefined' ) {
    return;
}

function with_jquery(f) {
    let script = document.createElement('script');
    script.type = 'text/javascript';
    script.textContent = `
if (window.jQuery) (${f.toString()})(window.jQuery);

//# sourceURL=${encodeURI(GM_info.script.namespace.replace(/\/?$/, '/'))}${encodeURIComponent(GM_info.script.name)}
`; // make this easier to debug
    document.body.appendChild(script);
}

with_jquery(($) => {
    function main() {
        let links = [
            new Link('timeline', 'Δ'),
            new Link('revisions', 'ℜ')
        ];
        $(() => {
            let pageHandler = getPageHandler(document);
            if (!pageHandler) return;
            pageHandler.getPosts().each(function() {
                let postHandler = getPostHandler(pageHandler, this);
                if (!postHandler) return;
                postHandler.addLinks(links);
            });
        });
    }
    function getPageHandler(container) {
        if ($('body', container).hasClass('question-page')) return new QuestionPageHandler(container);
        return null;
    }
    function getPostHandler(pageHandler, container) {
        if ($(container).hasClass('question')) return new QuestionPostHandler(pageHandler, container);
        if ($(container).hasClass('answer')) return new AnswerPostHandler(pageHandler, container);
        return null;
    }

    class Link {
        constructor(name, shortName) {
            this.name = name;
            this.shortName = shortName;
        }
        getUrl(id) {
            return `/posts/${id}/${this.name}`;
        }
    }

    class PageHandler {
        constructor(container) {
            this.container = container;
        }
        getPosts() {
            return $(this.container).find(this.postSelector);
        }
        getLabel(link) {
            return link.name;
        }
    }
    class QuestionPageHandler extends PageHandler {
        constructor(container) {
            super(container);
        }
        get postSelector() {
            return 'div.question, div.answer';
        }
    }

    class PostHandler {
        constructor(pageHandler, container) {
            this.pageHandler = pageHandler;
            this.container = container;
        }
        getId() {
            return $(this.container).data(this.idSelector);
        }
        addLinks(links) {
            let editLink = $(this.container).find('.edit-post, .suggest-edit-post, *[id^="edit-pending-"]');
            let separator = editLink.prev('.lsep');
            let lastLink = editLink;
            for (let link of links) {
                if (this.shouldInsertLink(link)) {
                    let newLink = this.createLink(link);
                    lastLink.after(separator.clone(), newLink);
                    lastLink = newLink;
                }
            }
        }
        shouldInsertLink(link) {
            if (link.name === 'revisions' && this.hasModifications()) {
                return false;
            }
            return true;
        }
        hasModifications() {
            // if modified, there will be an extra post signature, the edit signature
            return this.getContent().find('.post-signature').length > 1;
        }
        getContent() {
            return $(this.contentSelector, this.container);
        }
        createLink(link) {
            return $('<a></a>', {
                href: link.getUrl(this.getId()),
                class: `${link.name}-link`,
                title: this.getTitle(link),
                text: this.getLabel(link)
            });
        }
        getTitle(link) {
            return `view the ${link.name} for this ${this.containerName}`;
        }
        getLabel(link) {
            return this.pageHandler.getLabel(link);
        }
    }
    class QuestionPostHandler extends PostHandler {
        constructor(pageHandler, container) {
            super(pageHandler, container);
        }
        get containerName() {
            return 'post';
        }
        get idSelector() {
            return 'questionid';
        }
        get contentSelector() {
            return '.postcell';
        }
    }
    class AnswerPostHandler extends PostHandler {
        constructor(pageHandler, container) {
            super(pageHandler, container);
        }
        get containerName() {
            return 'answer';
        }
        get idSelector() {
            return 'answerid';
        }
        get contentSelector() {
            return '.answercell';
        }
    }
    main();
});

FYI, this won't be automatically installable to test in Tampermonkey unless you rename this to .user.js. Otherwise it is not detected properly and leaves it to the user to paste into their own local script.