---
url: https://desktop.bas.dev/desktop-shell/window-state.md
---
# Window state

`createWindowState` keeps where each window stood, so it opens there again: its size, its place, and whether it was maximized or in full screen. The app chooses the key a window is kept under, such as `main`, or the project a window shows.

```ts
import { createWindowState, fileStorage } from '@basmilius/desktop-shell';

const windowState = createWindowState({
    storage: fileStorage(join(app.getPath('userData'), 'window-state.json')),
    displays: () => screen.getAllDisplays(),
    defaults: { width: 1440, height: 900 }
});

const createWindow = (): BrowserWindow => {
    const window = new BrowserWindow({ ...windowState.bounds('main'), minWidth: 800, minHeight: 500, show: false });
    windowState.track('main', window);
    window.once('ready-to-show', () => window.show());
    return window;
};

app.on('before-quit', () => windowState.flush());
```

`bounds` goes into the constructor. `track` follows the window from then on; call it right after constructing the window, before it is shown, since it maximizes the window or puts it in full screen again once the window is ready to show.

## When it writes

Half a second after a window stops moving or resizing, at once when it closes, and on `flush`, for the moment the app quits. The bounds are always the window's normal ones, so a window that was maximized comes back maximized, and at its own size once a person unmaximizes it.

## Displays that changed

A display that was unplugged or rearranged would leave saved bounds off screen. `fitBounds` keeps them only while a display still shows enough of the window to grab its title bar (`VISIBLE_EDGE`), moves it fully onto that display and shrinks it to the display's work area. Otherwise the window opens at its default size, which Electron centers.

## Storage

`fileStorage` writes one JSON file through a file beside it, so a crash halfway leaves the last whole one. A file that does not parse, from another version, or with an entry that is not whole pixels is read as far as it holds; the rest opens at the default.