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Save hashes of displayed comments locally and mark new ones when displayed for the first time
// ==UserScript==
// @name HN: style unread content
// @description Save hashes of displayed comments locally and mark new ones when displayed for the first time
// @namespace myfonj
// @match https://news.ycombinator.com/*
// @grant none
// @version 1.1.1
// @author myfonj
// @run-at document end
// ==/UserScript==
// https://greasyfork.org/en/scripts/423969/versions/new
/*
* Changelog
* 1.1.1 (2023-10-22) visualise age (=offset) original post date (= dotted line) and points × comments
*/
// kinda sorta configuration
const WATCHED_ELEMENTS_SELECTOR = '.commtext, .storylink, .titlelink, .titleline > a';
const VIEWPORT_EXPOSITION_DURATION_UNTIL_READ = 900;
const CSS_CLASSES = {
unread: 'new',
read: 'read',
old: 'old'
};
// Styling. Very lame for now.
const CSS_STR = `
.${CSS_CLASSES.unread} {
border-right: 2px solid #3F36;
display: block;
padding-right: 1em;
}
.${CSS_CLASSES.read} {
border-right: 2px solid #0F03;
display: block;
padding-right: 1em;
}
.${CSS_CLASSES.old} {
opacity: 0.9;
}
/*
visualise age (=offset) original post date (= dotted line) and points × comments
*/
.subline {
position: relative;
}
.subline::before ,
.subline::after {
position: absolute;
right: 100%;
bottom: 0;
content: '';
background-color: lime;
width: calc(var(--points) * 1px);
height: calc(var(--comments) * 1px);
z-index: 1000000;
/* 0min = 1 */
/* 1min = .9 */
/* 10min = .8 */
--_minutes_old: calc(var(--age) / 1000 / 60);
--_minutes_old2: calc(var(--age2) / 1000 / 60);
--_o: calc( var(--_minutes_old) / 10 );
opacity: .5;
border: 1px solid red;
transform: scale(.2) translatex(calc(var(--_minutes_old2) * -1px));
transform-origin: bottom right;
}
.subline::after {
height: 0px;
width: calc(( var(--_minutes_old) - var(--_minutes_old2) )* 1px);
border: none;
border-bottom: 10px dotted lime;
background-color: transparent;
}
`;
// base64 'SHA-1' digest hash = 28 characters;
// most probably ending with '=' always(?)
const HASH_DIGEST_ALGO = 'SHA-1';
// local storage key
const LS_KEY = 'displayed_hashes_' + HASH_DIGEST_ALGO;
// actual code, yo
document.head.appendChild(document.createElement('style'))
.textContent = CSS_STR;
// TODO mutation observer for client-side rendered pages
// not case for HN, but it will make this truly universal
const ELS_TO_WATCH = document.querySelectorAll(WATCHED_ELEMENTS_SELECTOR);
/**
* watched DOM node -> it's text content digest
*/
const MAP_EL_HASH = new WeakMap();
/**
* watched DOM node -> time counter ID
*/
const MAP_EL_TIMEOUT_ID = new WeakMap();
/**
* get all "read" digests
*/
const GET_SEEN_HASHES_SET =
() => new Set((localStorage.getItem(LS_KEY) || '').split(','));
/**
* intersection observer callback
*/
const VIEWPORT_ENTRY_CHECKER = (entry) => {
const TGT = entry.target;
if (entry.isIntersecting) {
// entered viewport
if (MAP_EL_TIMEOUT_ID.get(TGT)) {
// already measuring - quick re-entry
return
}
// measure time in viewport
MAP_EL_TIMEOUT_ID.set(
TGT,
window.setTimeout(
processVisibleEntry,
VIEWPORT_EXPOSITION_DURATION_UNTIL_READ
)
);
} else {
// left viewport
MAP_EL_TIMEOUT_ID.delete(TGT);
}
function processVisibleEntry() {
if (MAP_EL_TIMEOUT_ID.get(TGT)) {
// HA! STILL in viewport!
// mark as read
TGT.classList.remove(CSS_CLASSES.unread);
TGT.classList.add(CSS_CLASSES.read);
const NEW_SET = GET_SEEN_HASHES_SET();
NEW_SET.add(MAP_EL_HASH.get(TGT))
MAP_EL_TIMEOUT_ID.delete(TGT);
// not interested in this element anymore
VIEWPORT_OBSERVER.unobserve(TGT);
// TODO move the persistence to window unload and/or blur event for fewer LS writes
localStorage.setItem(
LS_KEY,
Array.from(NEW_SET).join(',')
);
}
}
}
/**
* just a single observer for all watched elements
*/
const VIEWPORT_OBSERVER = new IntersectionObserver(
(entries, observer) => {
entries.forEach(_ => VIEWPORT_ENTRY_CHECKER(_));
},
{
root: null,
rootMargin: "-9%", // TODO use computed "lines" height here instead?
threshold: 0
}
);
const SEEN_ON_LOAD = GET_SEEN_HASHES_SET();
// compute hash, look into list and mark and observe "new" items
ELS_TO_WATCH.forEach(async el => {
const hash = await makeHash(el.textContent);
if (SEEN_ON_LOAD.has(hash)) {
el.classList.add(CSS_CLASSES.old);
return;
}
el.classList.add(CSS_CLASSES.unread);
MAP_EL_HASH.set(el, hash);
VIEWPORT_OBSERVER.observe(el);
});
/**
* string to base64 hash digest using native Crypto API
* @param {string} input
*/
async function makeHash (input) {
return btoa(
String.fromCharCode.apply(
null,
new Uint8Array(
await crypto.subtle.digest(
HASH_DIGEST_ALGO,
(new TextEncoder()).encode(input)
)
)
)
);
};
// unrelated add some links along "threads"
const threadsLink = document.querySelector('a[href^="threads"]');
const addLink = (key) => {
const l = threadsLink.cloneNode(true);
l.setAttribute('href', l.getAttribute('href').replace('threads', key));
l.textContent = key;
threadsLink.parentNode.insertBefore(l,threadsLink);
}
['upvoted','favorites'].forEach(addLink);
/*
// also not closely related: create velocity rectangles
// this time tailored to HN structure
tr[id="<numbers>"]
tr
td[colspan="2"]
td[class="subtext"]
span[class="subline"]
span[class="score"][id="score_<numbers>"] "<##> points"
a[class="hnuser"]
span[class="age"][title="<isodate>"]
...
a[href="item?id=<numbers>"] "<##> comments"
*/
const now = Date.now();
Array.from(document.querySelectorAll('.subline'))
.forEach(subline=>{
const tr = subline.closest('tr');
const age_el = subline.querySelector('.age');
const age_title = age_el.getAttribute('title');
const age_text = age_el.textContent;
const age_ms = now - (new Date(age_title + 'Z')).getTime();
const age2_ms = textAgeToMS(age_text);
subline.querySelector('.age').textContent += ' (' + (age_ms / 1000 / 60 / 60).toFixed(2) + 'h)';
const points_count = (subline.querySelector('.score')?.textContent?.match(/\d+/)||['1'])[0] * 1;
const comments_count = (subline.querySelector('& > a:last-child')?.textContent?.match(/\d+/)||['1'])[0] * 1;
subline.style.setProperty('--age', age_ms);
subline.style.setProperty('--age2', age2_ms);
subline.style.setProperty('--points', points_count);
subline.style.setProperty('--comments', comments_count);
})
function textAgeToMS(text) {
const rx = /^([0-9]+)\s+(\S+)/;
const match = text.match(rx);
const secondsDurationsNames = {
second: 1,
minute: 1 * 60,
hour: 1 * 60 * 60,
day: 1 * 60 * 60 * 24,
month: 1 * 60 * 60 * 24 * 30,
year: 1 * 60 * 60 * 24 * 30 * 365,
};
const amount = Number(match[1]);
const unit = match[2].replace(/s$/,'');
const secondsPerUnit = secondsDurationsNames[unit];
return 1000 * amount * secondsPerUnit;
}
function msToHours(ms) {
return ms / 1000 / 60 / 60;
}