---
last_modified: 2026-06-16
title: "Dialogs"
description: "prompt(), alert(), and confirm() show native popup dialogs in deno desktop apps instead of terminal prompts."
---

:::info Coming in Deno 2.9

`deno desktop` ships in Deno v2.9.0 and is not in a stable release yet. To try
it now, run `deno upgrade canary` to install the
[`canary`](/runtime/reference/cli/upgrade/) build. The command, configuration
keys, and TypeScript APIs may still change before the feature is stable.

:::

The familiar browser globals `prompt()`, `alert()`, and `confirm()` work inside
`deno desktop` apps, but instead of reading from the terminal, they show
**native popup dialogs**.

This makes desktop apps feel native without any platform-specific code, and
keeps the same API you would write for a browser-side script.

## `alert(message)`

Shows a modal dialog with an OK button. Returns `void`.

```ts
alert("Save complete.");
```

The current window is the parent: clicking outside the dialog does not dismiss
it; the user must click OK.

## `confirm(message)`

Shows a modal dialog with OK and Cancel. Returns `boolean`: `true` for OK,
`false` for Cancel.

```ts
if (confirm("Discard unsaved changes?")) {
  await closeDocument();
}
```

## `prompt(message, defaultValue?)`

Shows a modal dialog with a text input plus OK and Cancel. Returns the entered
string, or `null` if the user cancelled.

```ts
const name = prompt("New document name:", "Untitled");
if (name !== null) {
  await createDocument(name);
}
```

## When they fire

These functions block the calling code (synchronously) until the user responds.
They run **on the Deno runtime thread**, not the webview, so they do not freeze
the rendered UI, but they do pause your handler.

```ts
win.addEventListener("menuclick", (e) => {
  if (e.detail.id === "delete") {
    if (confirm("Really delete?")) {
      // … do the deletion
    }
  }
});
```

If you call them from the webview side (via JavaScript inside the rendered
page), the webview's own native dialogs are used instead: `window.alert()`,
`window.confirm()`, and `window.prompt()` as the browser implements them. The
behavior is similar: a native modal scoped to that webview.

## Differences from terminal Deno

In a normal `deno run` script, these functions read from / write to the
terminal: `prompt` reads a line of stdin, `confirm` accepts `y` / `n`. That
terminal behavior would be invisible inside a desktop app, so `deno desktop`
swaps them out for native dialogs without any code change on your part.

## File and folder dialogs

Native file-picker and folder-picker dialogs are not yet exposed as a
first-class API. Until they are, two workarounds exist:

1. **Use the webview's `<input type="file">`**. The webview shows the OS-native
   picker, and the resulting `File` object can be sent over a binding for the
   Deno side to handle:

   ```html
   <input id="f" type="file" accept=".json">
   <script>
     document.getElementById("f").addEventListener("change", async (e) => {
       const file = e.target.files[0];
       await bindings.handleFile(file.name, await file.arrayBuffer());
     });
   </script>
   ```

   ```ts
   win.bind("handleFile", async (name, bytes) => {
     await Deno.writeFile(name + ".bak", new Uint8Array(bytes));
   });
   ```

2. **Drag-and-drop into the webview**. Drop a file onto a `<div>`, read it with
   the File API, and pass the bytes through a binding.

A native file-picker API is on the roadmap.

## Notifications

System notifications have a dedicated API: the standard Web `Notification`
constructor, callable from your Deno-side code. See
[Notifications](/runtime/desktop/notifications/).

## Clipboard

A dedicated clipboard API is not yet exposed. Use the Web `Clipboard` API
(`navigator.clipboard.readText()`, `writeText()`) from the webview side for now.