messageDisplayScripts API

This message display scripts API first appeared in Thunderbird 78. Functionally it is the same as the content scripts API except that it works on the document of email messages being displayed. See the MDN documentation for a more in-depth explanation and Thunderbird 82 Beta for examples.

Note

Registering a message display script in the manifest.json file is not possible at this point.

Permissions

messagesModify

Read and modify your email messages as they are displayed to you

Note

The permission messagesModify is required to use messenger.messageDisplayScripts.*.

Functions

register(messageDisplayScriptOptions)

Register a message display script programmatically

Parameters

messageDisplayScriptOptions

(RegisteredMessageDisplayScriptOptions)

Required permissions

messagesModify

Types

RegisteredMessageDisplayScript

An object that represents a message display script registered programmatically

object

unregister() Unregister a message display script registered programmatically

RegisteredMessageDisplayScriptOptions

Details of a message display script registered programmatically

object

[css]

(array of ExtensionFileOrCode, optional)

The list of CSS files to inject

[js]

(array of ExtensionFileOrCode, optional)

The list of JavaScript files to inject

External Types

The following types are not defined by this API, but by the underlying Mozilla WebExtension code base. They are included here, because there is no other public documentation available.

ExtensionFileOrCode

Specify code, either by pointing to a file or by providing the code directly. Only one of the two is allowed.

object

code

(string)

Some JavaScript code to register.

file

(string)

A URL starting at the extension’s manifest.json and pointing to a JavaScript file to register.