reddit-compact-redirect.user.js

// ==UserScript==
// @name         Reddit Compact redirect
// @version      0.2
// @description  Converts reddit.com/* links to reddit.com/*/.i links
// @author       turboevoluzione
// @match        *://*.reddit.com/*
// @exclude      *://old.reddit.com/*
// @grant        none
// @run-at       document-start
// ==/UserScript==

/*
 * Checks whether the URL must be changed.
 */
function testUrl(location) {
    var url = new URL(location);

    if (url.hostname.endsWith('reddit.com')) {
        var isCompact = url.pathname.endsWith('/.i');
        var isOld = url.hostname == 'old.reddit.com';
        var isSpecial = url.pathname.indexOf('/gallery/') > -1
            || url.pathname.indexOf('/svc/') > -1
            || url.pathname.indexOf('/u/') > -1
            || url.pathname.indexOf('/s/') > -1
            || url.pathname.indexOf('/gallery/') > -1
            || url.pathname.endsWith('/media')
            || url.pathname.endsWith('/logout');

        return !!!(isCompact
            || isOld
            || isSpecial);
    }

    return false;
}

/*
 * Modifies the URL accordingly.
 */
function getCompactUrl(location) {
    var url = new URL(location);

    if (url.pathname.endsWith('/.i'))
        return url.href;

    if (url.pathname.endsWith('.compact'))
        url.pathname = url.pathname.replace('.compact', '/.i');
    else
        url.pathname = url.pathname.concat('/.i');

    url.pathname = url.pathname.replace('//.i', '/.i');

    return url;
}

/*
 * Fixes the links in the page.
 */
function fixRedditLinks() {
    // Obtain the links.
    var links = Array.prototype.slice.call(document.links, 0);

    // Filter the links by their URL.
    links.filter(function (link) {
        if (testUrl(link)) {
            var compactUrl = getCompactUrl(link);

            if (link.hasAttribute('data-outbound-url'))
                link.setAttribute('data-outbound-url', compactUrl.href);
            link.setAttribute('href', compactUrl.href);
        }
    });
}

// Check the current URL.
if (testUrl(document.location)) {
    // Redirect to the new URL.
    document.location.replace(getCompactUrl(window.location));
}

window.onload = fixRedditLinks;
setInterval(fixRedditLinks, 50);