4chan-auto-watcher

a script to automatically watch 4chan threads matching a pattern
Ask a question, post a review, or report the script.
Wrap lines
// ==UserScript==
// @name        4chan-auto-watcher
// @namespace   github.com/diegostafa/userscripts
// @match       https://boards.4chan.org/*/catalog
// @match       https://boards.4channel.org/*/catalog
// @version     3
// @author      Diego <[email protected]> (github.com/diegostafa)
// @description a script to automatically watch 4chan threads matching a pattern
// @run-at      document-end
// ==/UserScript==

const currentBoard = window.location.pathname.split("/").filter((s) => s !== "")[0];

let boardsAndFilters = [
  ["", /^[^a-z]*$/],
];

const buildUi = () => {

  const createButton = (text) => {
    let button = document.createElement("div");
    button.innerHTML = text;
    button.style.backgroundColor = "#444444";
    button.style.color = "white";
    button.style.textAlign = "center";
    button.style.border = "none";
    button.style.padding = "2px";
    button.style.cursor = "pointer";
    return button;
  };

  const createAutowatchButton = () => {
    let button = createButton("autowatch");
    button.addEventListener("click", () => { autoWatch(); });
    return button;
  };

  const createConfigButton = () => {
    let button = createButton("config");

    button.addEventListener("click", () => {
      var win = window.open("", "Autowatch config", "toolbar=no");
      win.document.body.innerHTML = `TODO`;

    });

    return button;
  };

  let threadWatcher = document.getElementById("threadWatcher");
  let btnContainer = document.createElement("div");

  btnContainer.style.display = "grid";
  btnContainer.style.gridTemplateColumns = "100%";
  btnContainer.style.gridGap = "2px";
  // btnContainer.appendChild(createConfigButton());
  btnContainer.appendChild(createAutowatchButton());

  threadWatcher.appendChild(btnContainer);
};

const isThreadMatching = (filters) => (thread) => {
  const teaser = thread.querySelector('.teaser');

  if (!teaser) return false;

  return filters.reduce(
    (acc, [board, filter]) =>
      acc = acc || (filter.test(teaser.textContent) && (board === "" || currentBoard === board)), false);
};

const autoWatch = () => {
  let threads = Array.from(document.querySelectorAll('#threads .thread'));

  threads
    .filter(isThreadMatching(boardsAndFilters))
    .map((thread) => thread.querySelector('span.watchIcon'))
    .filter((watchIcon) => watchIcon !== null)
    .forEach((watchIcon) => watchIcon.click());
};

buildUi();