Google has announced third-party add-ons for Google Docs and Sheets. As part of the launch, Google is opening up a developer-preview phase for developers to create their own add-ons.
“If you have a cool idea for Docs and Sheets users, we’d love to publish your code in the add-on store and get it in front of millions of users,” wrote Dan Lazin, technical writer for the Google Apps team, in the company’s Developers Blog.
Add-ons are currently in developer preview, but the tools and APIs are available to everyone, according to Lazin. The only constraint is publication. Only approved developers can publish their add-ons to the store. Developers must obtain approval before publishing an add-on; Google recommended applying once the add-on is ready to be launched.
To obtain approval, add-ons must meet the following checklist provided by Google:
• The design adheres to the UI style guide.
• The script includes an onInstall() function that populates the menu (usually by calling onOpen()).
• To comply with the limitations of the no-authorization mode, the script’s global code and the AuthMode.NONE path of the onOpen(e) function do not contain calls to services that require authentication.
• The script has been tested with multiple user accounts collaborating in a document.
• The script has error-handling code and only shows appropriate error messages to the user.
• The script’s project name is the same as the name intended for publication. (The script name appears in the authorization dialog.)
Add-on restrictions include the inability to change features in Google Apps, charge users for installation, run add-ons automatically, and detect user actions.
Google also announced that add-ons for Google Forms are on their way.
More information about building an add-on for Google is available here.