---
title: sidebarAction.getPanel()
slug: Mozilla/Add-ons/WebExtensions/API/sidebarAction/getPanel
tags:
  - API
  - Add-ons
  - Extensions
  - Method
  - Reference
  - WebExtensions
  - getPanel
  - sidebarAction
browser-compat: webextensions.api.sidebarAction.getPanel
---
{{AddonSidebar()}}

Gets a URL to the HTML document that defines the sidebar's contents.

This is an asynchronous function that returns a [`Promise`](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise).

## Syntax

```js
var gettingPanel = browser.sidebarAction.getPanel(
  details               // object
)
```

### Parameters

- `details`

  - : `object`. An object with the following properties:

    - `tabId`{{optional_inline}}
      - : `integer`. Get the panel for the sidebar specific to the given tab.
    - `windowId` {{optional_inline}}
      - : `integer`. Get the panel for the sidebar specific to the given window.

<!---->

- If `windowId` and `tabId` are both supplied, the function fails and the promise it returns is rejected.
- If `windowId` and `tabId` are both omitted, the global panel is returned.

### Return value

A [`Promise`](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) that will be fulfilled with a string containing the URL for the panel's document. This will be a fully qualified URL, such as:

```
moz-extension://d1d8a2eb-fe60-f646-af30-a866c5b39942/sidebar.html
```

## Browser compatibility

{{Compat}}

## Examples

Get the panel's URL:

```js
function onGot(sidebarUrl) {
  console.log(sidebarUrl);
}

var gettingPanel = browser.sidebarAction.getPanel({});
gettingPanel.then(onGot);
```

{{WebExtExamples}}

> **Note:** This API is based on Opera's [`chrome.sidebarAction`](https://dev.opera.com/extensions/sidebar-action-api/) API.
>
> Microsoft Edge compatibility data is supplied by Microsoft Corporation and is included here under the Creative Commons Attribution 3.0 United States License.

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