webextensions-examples/dnr-block-only/README.md

dnr-block-only

Demonstrates how to block network requests without host permissions using the declarativeNetRequest API with the declarative_net_request manifest key.

What it does

This extension blocks:

• network requests to URLs containing "blocksub" (except for top-level navigations).
• top-level navigation to URLs containing "blocktop".
• all requests containing "blockall".

Load testpage.html to see the extension in action. This demo page does not need to be packaged with the extension.

What it shows

This example shows how to:

• use the declarativeNetRequest API through the declarative_net_request manifest key.
• use the "resourceTypes" and "excludedResourceTypes" conditions of a declarativeNetRequest rule.
• block network requests without host permissions using the "declarativeNetRequest" permission, which triggers the "Block content on any page" permission warning at install time.

This example is the only cross-browser way to block network requests (at least in Firefox, Chrome, and Safari). The webRequest API is an alternative way to implement this functionality, but is only available in Firefox (MV2 and MV3) and in Chrome (MV2 only). Safari does not support the webRequest API.

Comparison with Manifest Version 2

While this example uses "manifest_version": 3, the functionality is not specific to Manifest Version 3.

To create a MV2 version of the extension, modify manifest.json as follows:

• Set manifest_version to 2.

Index of DNR examples

• dnr-block-only (this example)
• dnr-dynamic-with-options
• dnr-redirect-url