UserScript Force Spellcheck

force-spellcheck.js

// ==UserScript==
// @name         Force Spellcheck
// @namespace    https://example.com/
// @version      1.0
// @description  Force spellcheck = true on all textareas / inputs / contenteditable
// @match        *://*/*
// @grant        none
// ==/UserScript==

(function () {
  "use strict";

  function fix(el) {
    if (!el) return;
    // Only if element supports spellcheck
    if ("spellcheck" in el) {
      // set the property and attribute
      el.spellcheck = true;
      el.setAttribute("spellcheck", "true");
    }
  }

  function scanAll() {
    document.querySelectorAll('textarea, input, [contenteditable="true"]').forEach(fix);
  }

  // Initial pass
  scanAll();

  // Also do it on focus (some sites re-add or override)
  document.addEventListener("focusin", (ev) => {
    fix(ev.target);
  });

  // Observe dynamically added elements
  const mo = new MutationObserver((muts) => {
    for (const m of muts) {
      for (const node of m.addedNodes) {
        if (node.nodeType === Node.ELEMENT_NODE) {
          if (node.matches && node.matches('textarea, input, [contenteditable="true"]')) {
            fix(node);
          }
          node.querySelectorAll && node.querySelectorAll('textarea, input, [contenteditable="true"]').forEach(fix);
        }
      }
    }
  });

  mo.observe(document.documentElement, { childList: true, subtree: true });
})();