Displays deletion time on FoolFuuka archives. Red icons indicate moderation, as the time is outside of when a normal user can delete.

janny_calc.user.js

// ==UserScript==
// @name        Janny calc
// @namespace   Violentmonkey Scripts
// @include     http://archive.4plebs.org/*
// @include     https://archive.4plebs.org/*
// @include     http://archive.nyafuu.org/*
// @include     https://archive.nyafuu.org/*
// @include     http://desuarchive.org/*
// @include     https://desuarchive.org/*
// @include     http://arch.b4k.co/*
// @include     https://arch.b4k.co/*
// @include     http://boards.fireden.net/*
// @include     https://boards.fireden.net/*
// @include     http://archived.moe/*
// @include     https://archived.moe/*
// @include     http://archiveofsins.com/*
// @include     https://archiveofsins.com/*
// @include     http://thebarchive.com/*
// @include     https://thebarchive.com/*
// @include     http://www.tokyochronos.net/*
// @include     https://www.tokyochronos.net/*
// @include     https://archive.wakarimasen.moe/*
// @include     http://archive.wakarimasen.moe/*
// @include     http://archive.alice.al/*
// @include     https://archive.alice.al/*
// @include     https://archive.palanq.win/*
// @include     http://archive.palanq.win/*
// @grant       none
// @version     1.0
// @author      Anonymous
// @run-at document-idle
// @description 10/31/2021, 11:53:38 PM
// ==/UserScript==
const jannyRange = [1, 30];
const tr = {
  'Jan': '01',
  'Feb': '02',
  'Mar': '03',
  'Apr': '04',
  'May': '05',
  'Jun': '06',
  'Jul': '07',
  'Aug': '08',
  "Sep": '09',
  "Oct": '10',
  "Nov": '11',
  "Dec": '12'
}
function is_jannied(tmp, tmp2) {

    const date1   = new Date(tmp);
    const parts   = tmp2.split('on ')[1].replace(" at ", " ").replace(",", "").split(' ')
    const date2   = new Date(`${parts[2]}-${tr[parts[0]]}-${parts[1]}T${parts[3]}-00:00`)
    const min_dif = ( (date2 - date1) / 1000) / 60;
    if (min_dif < jannyRange[0] || min_dif > jannyRange[1]) {
        return [true, min_dif.toFixed(2)]
    }
    return [false, min_dif.toFixed(2)]
}

document.querySelectorAll('.post_data').forEach(
    function(el) {
        const trash = el.querySelector('.icon-trash');
        if (trash != null) {
            const date0 = el.querySelector('.time_wrap > time').dateTime;
            if (window.location.hostname == 'arch.b4k.co'){
              var date1 = trash.parentElement.title;
            } else {
              var date1 = trash.title;
              if (date1.includes('prematurely')) return
            }
            const ij    = is_jannied(date0, date1);
            trash.insertAdjacentHTML('afterbegin', ij[1]);
            if (ij[0]) {
                trash.style = 'color:red;';
            }
        }
    })