Debugging and common mistakes

See the errors

With developer mode on, uncaught errors from your theme show up as notices: “Theme: Uncaught SyntaxError: …”.
For the real developer tools (console, inspector, network):
1. Quit ejGames completely (quick menu → Quit ejGames).
2. Open it from a cmd window with remote debugging on:
  set WEBVIEW2_ADDITIONAL_BROWSER_ARGUMENTS=--remote-debugging-port=9222 "%LOCALAPPDATA%\ejGames\ejgames.exe"
  (change the path if you installed it somewhere else).
3. In Edge, open edge://inspect (if nothing appears, press Configure… and add localhost:9222) and press inspect on the iframe entry that starts with http://ejg-theme.localhost/ejemplo/. That is your theme’s console: console.log() writes there. You can also inspect the page http://tauri.localhost/ and pick the theme iframe in the console’s context selector (where it says “top”).

What a theme cannot do

The theme lives in a closed box, for safety. This does not work:

You want…	What happens	What to do
Data from the internet (`fetch`, an API)	blocked	Put everything you need inside the theme folder.
Fonts, images or scripts from the internet (Google Fonts, a CDN)	they do not load	Download them into the folder and use relative paths: `@font-face { src: url("fonts/my-font.woff2"); }`
Read your own files with `fetch("datos.json")`	also blocked: `fetch` only reaches library art (`http://ejg-media.localhost`)	Put the data in a JS module (`export default { … }`) and load it with `import datos from "./datos.js";`. The theme’s images, CSS, fonts, audio and video do load in their tags.
`localStorage`, `sessionStorage`, `IndexedDB`, cookies	they throw `SecurityError`	`ejg.storage` (below).
`alert()`, `confirm()`, `prompt()`	they do nothing	`ejg.ui.toast("Text", "info" \| "ok" \| "error")` or your own HTML dialog.
Open websites	`window.open` is blocked, and an `<a href="https://…">` link opens the site inside the theme, which then disappears (after a few seconds ejGames loads the house theme)	Do not link out to websites.
Reach the disk, other programs, or Tauri	impossible	Only what `window.ejg` offers.

To store things (the last game you opened, a filter…) use ejg.storage: each theme has 512 KB per profile and can store any JSON value.

await ejg.storage.set("ultimo", 42);
const ultimo = await ejg.storage.get("ultimo"); // 42 (undefined if it does not exist)
const todo = await ejg.storage.getAll();        // { ultimo: 42, … }

Because of these limits, installing someone else’s theme is safe. At most it can launch games from your library or open launcher screens.

Common mistakes

Symptom	Likely cause
The theme does not appear in the gallery	`theme.json` has errors, or the `id` is not valid (see `logs\ejgames.log`).
I changed `theme.json` and nothing happened	It has an error (the theme keeps the previous version): see the log.
I save and it does not reload	Developer mode is off. Meanwhile, F5.
Blank screen	A JavaScript error (turn on developer mode), a bad `import` (kit paths start with `/_sdk/kit/`, yours with `./`), or the `<script>` is missing `type="module"` (without it, `await` and `import` fail).
“isn’t responding. The house theme was loaded”	Your code blocks the page (a loop that never ends, a huge calculation at startup).
The controller never reaches a button	It is missing `data-focus`, or it is hidden or `disabled`.
The arrows escape a panel	Put `data-focus-trap` on the panel.
Esc closes your panel and ejGames also acts (in Big Picture, the quick menu opens)	Your `back` was not treated as handled. In `bindNav`, do not return `false` when you did use it.
After closing settings there is no focus	`ejg.on("focus-return", () => foco.restore())` is missing.
The focus ring is clipped	`content-visibility: auto` clips whatever sticks out. Leave `padding` on the card.
An element with `hidden` is still visible	Your CSS sets `display`. Add `[hidden] { display: none !important; }`.
A click at the top right does not land	That corner belongs to the launcher’s window buttons (`windowControls: "host"`).
A CSS variable does not apply from `h()`	With `style` as an object you cannot set variables. Use a string, `style: "--tono: 120"`.

Themes

Step by step

Debugging and common mistakes

See the errors

What a theme cannot do

Common mistakes

​See the errors

​What a theme cannot do

​Common mistakes

See the errors

What a theme cannot do

Common mistakes