Extending the Composer

The composer lies at the heart of Mailspring, and many improvements to the mail experience require deep integration with the composer. To enable these sort of plugins, the {DraftStore} exposes an extension API.

This API allows your package to:

• Display warning messages before a draft is sent. (ie: "Are you sure you want to send this without attaching a file?")

• Intercept keyboard and mouse events to the composer's text editor.

• Transform the draft and make additional changes before it is sent.

To create your own composer extensions, subclass {ComposerExtension} and override the methods your extension needs.

In the sample packages repository, templates is an example of a package which uses a ComposerExtension to enhance the composer experience.

Example

This extension displays a warning before sending a draft that contains the names of competitors' products. If the user proceeds to send the draft containing the words, it appends a disclaimer.

{ComposerExtension} = require 'nylas-exports'

class ProductsExtension extends ComposerExtension

   @warningsForSending: ({draft}) ->
      words = ['acme', 'anvil', 'tunnel', 'rocket', 'dynamite']
      body = draft.body.toLowercase()
      for word in words
        if body.indexOf(word) > 0
            return ["with the word '#{word}'?"]
      return []

   @applyTransformsForSending: ({draftBodyRootNode, draft}) ->
    if @warningsForSending({draft})
      el = document.createElement('p');
      el.innerText = "This email contains competitor's product names or trademarks used in context."
      draftBodyRootNode.appendChild(el)