| Type | Object |
|---|---|
| Mandatory | No |
| Example |
"background": {
"scripts": ["background.js"]
}
|
Use the background key to include one or more background scripts, and optionally a background page in your extension.
Background scripts are the place to put code that needs to maintain long-term state, or perform long-term operations, independently of the lifetime of any particular web pages or browser windows.
Background scripts are loaded as soon as the extension is loaded and stay loaded until the extension is disabled or uninstalled. You can use any of the WebExtension APIs in the script, as long as you have requested the necessary permissions.
See the "Background pages" section in Anatomy of an extension for some more details.
The background key is an object that may have one of the following two properties, both optional:
"scripts" |
An array of strings, each of which is a path to a JavaScript source. The path is relative to the manifest.json file itself. These are the background scripts that will be included in the extension. The scripts share the same The scripts are loaded in the order they appear in the array. Note that there is a bug affecting Firefox versions earlier than 50: when the Firefox debugger is open, scripts are not always loaded in the order given in the array. To work around this bug, you can use the |
"page" |
If you specify If you need some particular content in the page, you can define your own page using the If you use this property, you can no longer specify background scripts using |
Example
"background": {
"scripts": ["jquery.js", "my-background.js"]
}
Load two background scripts.
"background": {
"page": "my-background.html"
}
Load a custom background page.
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
| Chrome | Edge | Firefox | Firefox for Android | Opera | |
|---|---|---|---|---|---|
| Basic support | Yes | Yes 1 | 48 | 48 | Yes |
persistent | Yes | Yes | No | No | Yes |