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Troubleshooting

GAS logs everything to the browser console with a colored [GAS] prefix. Open DevTools (F12 → Console) first — the answer is usually already there. The window.GAS debug API is your best friend below.

The toolbar button doesn't appear​

GitHub is a single-page app and its DOM changes frequently. Work through this checklist:

  1. Hard-reload the page (Ctrl/Cmd + Shift + R) and look for the [GAS] Starting GAS banner confirming the script is running at all. No banner → the script isn't running: check your manager's toggle and that the URL matches @match https://github.com/*.

  2. Rescan manually:

    GAS.scan()
    // → array of detected editors; also logs
    //   "Scan result: N editor(s), M button(s) handled."

  3. Inspect what GAS sees:

    GAS.editors()   // console.table of every candidate editor
    GAS.buttons()   // console.table of injected buttons (check 'connected')

  4. Interpret the table. If GAS.editors() returns an empty table on a page with a comment box, GitHub changed its markup and the editor heuristics no longer match — please open an issue with the console output (GAS also runs a pageDebug() dump on load).

  5. If the editor is found but no button is injected, findToolbar() couldn't locate a formatting toolbar (it looks for [role="toolbar"] near the editor, or [role="toolbar"][aria-label*="Formatting"] up to 8 ancestors). Also a markup-change symptom — issue welcome.

Why scanning is continuous

A MutationObserver on document.body triggers a debounced re-scan (100 ms) whenever nodes are added. So the button should eventually appear — e.g. after lazy-loading a comment box. If it never does, that's the heuristic mismatch above, not a timing problem.

The picker opens but images never load​

  • Check DevTools → Network for blocked raw.githubusercontent.com requests (ad blockers, corporate proxies and strict CSP extensions sometimes block it).
  • Try opening the image URL directly in a new tab. GAS pulls emoji from raw.githubusercontent.com/.../res/img/....

An emoji image shows dimmed/broken​

The picker sets opacity: 0.35 on images that fire an error event. If a card is dimmed, its URL is dead or unreachable. For bundled emoji this means the repo file moved — report it. For custom entries, re-check your url (Custom emoji).

The emoji inserts but disappears when editing / previewing​

This means GitHub's internal state wasn't notified of the DOM change. GAS already handles it:

  • for textarea editors it sets the value via the native prototype setter and then dispatches bubbling input and change events (setTextareaValue)
  • for contenteditable editors it uses a Range insertion and dispatches a bubbling InputEvent with inputType: 'insertElement'

If you still see desync on some exotic editor, capture it with GAS.editors() and open an issue.

The toolbar button throws after I edited DEFAULT_GAS​

createGASButton() builds its icon by looking up the entry named trollge:

const icon = DEFAULT_GAS.find(gas => gas.name === 'trollge');
image.src = icon.url; // TypeError if that entry is gone

If you renamed or deleted trollge, restore the entry (or keep one entry named trollge and point url at whatever you like). Details in API reference → createGASButton.

The picker closes "by itself"​

That's by design — it closes on scroll and resize (its position would otherwise be stale), and on Esc or any outside click. Repositioning is cheap, so just reopen it. See Using the picker.

Duplicate buttons in one toolbar​

Shouldn't happen: injectButton() skips toolbars that already contain a [data-gas-button="true"] element and marks editors with data-gas-processed="true". If you do see duplicates, two copies of the script are running (e.g. installed in two managers, or pasted twice). Check GAS.buttons() and your manager dashboards.

Still stuck?​

Open an issue and include:

  • the full [GAS] console log (from the banner down),
  • output of GAS.editors() and GAS.buttons(),
  • your browser + userscript manager versions,
  • the GitHub page URL where it fails.