// ==UserScript==
// @name MeFi Navigator Redux
// @namespace https://github.com/klipspringr/mefi-userscripts
// @version 2025-08-14-a
// @description MetaFilter: navigate through users' comments, and highlight comments by OP and yourself
// @author Klipspringer
// @supportURL https://github.com/klipspringr/mefi-userscripts
// @license MIT
// @match *://*.metafilter.com/*
// @grant none
// ==/UserScript==
(() => {
"use strict";
if (
!/^\/(\d|comments\.mefi)/.test(window.location.pathname) ||
/rss$/.test(window.location.pathname)
) {
return;
}
const SVG_UP = `<svg xmlns="http://www.w3.org/2000/svg" hidden style="display:none"><path id="mfnr-up" fill="currentColor" d="M 0 93.339 L 50 6.661 L 100 93.339 L 50 64.399 L 0 93.339 Z" /></svg>`;
const SVG_DOWN = `<svg xmlns="http://www.w3.org/2000/svg" hidden style="display:none"><path id="mfnr-down" fill="currentColor" d="M 100 6.69 L 50 93.31 L 0 6.69 L 50 35.607 L 100 6.69 Z" /></svg>`;
// CSS notes:
// - mfnr-op needs to play nicely with .mod in threads where OP is a mod
// - classic theme has different margins from modern, so we can't change margin-left without knowing what theme we're on
// - relative positioning seems to work better
const CLASSES = `<style>
.mfnr-op {
border-left: 5px solid #0004 !important;
padding-left: 10px !important;
position: relative !important;
left: -15px !important;
}
@media (max-width: 550px) {
.mfnr-op {
left: -5px !important;
}
}
.mfnr-self-badge {
background-color: #C8E0A1;
border-radius: 2px;
color: #000;
font-size: 0.8em;
margin-left: 4px;
padding: 0 4px;
cursor: default;
}
.mfnr-nav {
white-space: nowrap;
}
.mfnr-nav svg {
vertical-align: middle;
top: -1px;
}
</style>`;
const ATTR_BYLINE = "data-mfnr-byline";
const getCookie = (key) => {
const s = RegExp(key + "=([^;]+)").exec(document.cookie);
if (!s || !s[1]) return null;
return decodeURIComponent(s[1]);
};
const markSelf = (targetNode) => {
const span = document.createElement("span");
span.classList.add("mfnr-self-badge");
span.textContent = "me";
targetNode.after(span);
};
const markOP = (targetNode) =>
targetNode.parentElement.parentElement.classList.add("mfnr-op");
const createLink = (href, svgHref) => {
const a = document.createElement("a");
a.setAttribute("href", "#" + href);
const svg = document.createElementNS(
"http://www.w3.org/2000/svg",
"svg"
);
svg.setAttribute("width", "1em");
svg.setAttribute("viewBox", "0 0 100 100");
svg.setAttribute("class", "mfnr-nav");
const use = document.createElementNS(
"http://www.w3.org/2000/svg",
"use"
);
use.setAttribute("href", "#" + svgHref);
svg.appendChild(use);
a.appendChild(svg);
return a;
};
const processByline = (
bylineNode,
user,
anchor,
anchors,
firstRun,
self = null,
op = null
) => {
// don't mark self or OP more than once
if (firstRun || !bylineNode.hasAttribute(ATTR_BYLINE)) {
if (self !== null && user === self) markSelf(bylineNode);
if (op !== null && user === op) markOP(bylineNode);
bylineNode.setAttribute(ATTR_BYLINE, "");
}
if (anchors.length <= 1) return;
const i = anchors.indexOf(anchor);
const previous = anchors[i - 1];
const next = anchors[i + 1];
const navigator = document.createElement("span");
navigator.setAttribute("class", "mfnr-nav");
const nodes = ["["];
if (previous) nodes.push(createLink(previous, "mfnr-up"));
nodes.push(anchors.length);
if (next) nodes.push(createLink(next, "mfnr-down"));
nodes.push("]");
navigator.append(...nodes);
bylineNode.parentElement.appendChild(navigator);
};
const run = (subsite, self, firstRun) => {
const start = performance.now();
const opHighlight = subsite !== "ask" && subsite !== "projects"; // don't highlight OP on subsites with this built in
// if not first run, remove any existing navigators (from both post and comments)
if (!firstRun)
document
.querySelectorAll("span.mfnr-nav")
.forEach((n) => n.remove());
// post node
// tested on all subsites, modern and classic, 2025-04-10
const postNode = document.querySelector(
"div.copy > span.smallcopy > a:first-child"
);
const op = postNode.textContent.trim();
// initialise with post
const bylines = [[op, "top"]];
const mapUsersAnchors = new Map([[op, ["top"]]]);
// comment nodes, excluding live preview
// tested on all subsites, modern and classic, 2025-04-10
const commentNodes = document.querySelectorAll(
"div.comments:not(#commentform *) > span.smallcopy > a:first-child"
);
for (const node of commentNodes) {
const user = node.textContent.trim();
const anchorElement =
node.parentElement.parentElement.previousElementSibling;
const anchor = anchorElement.getAttribute("name");
bylines.push([user, anchor]);
const anchors = mapUsersAnchors.get(user) ?? [];
mapUsersAnchors.set(user, anchors.concat(anchor));
}
for (const [i, bylineNode] of [postNode, ...commentNodes].entries())
processByline(
bylineNode,
bylines[i][0],
bylines[i][1],
mapUsersAnchors.get(bylines[i][0]),
firstRun,
self,
opHighlight && i > 0 ? op : null
);
console.log(
"mefi-navigator-redux",
firstRun ? "first-run" : "new-comments",
1 + commentNodes.length,
Math.round(performance.now() - start) + "ms"
);
};
document.body.insertAdjacentHTML("beforeend", SVG_UP + SVG_DOWN);
document.body.insertAdjacentHTML("beforeend", CLASSES);
const subsite = window.location.hostname.split(".", 1)[0];
const self = getCookie("USER_NAME");
const newCommentsElement = document.getElementById("newcomments");
if (newCommentsElement) {
const observer = new MutationObserver(() => run(subsite, self, false));
observer.observe(newCommentsElement, { childList: true });
}
run(subsite, self, true);
})();
