Important

This documentation is deprecated, and only kept here to support users of browser extension APIs. If you are using Trigger.io for iOS or Android, see https://trigger.io/docs/.

Browser Add-on Concepts

NB this documentation only concerns browser extensions, not mobile apps.

Extensions built on the Forge platform have two main aspects:

1. code to run when the browser is started
2. code to run when a page loads

Code run at startup: "background code"

If your extension relies on long-running code which is not attached or associated with any particular web page, you should use background code.

This code is loaded once when the browser is open or extensions is loaded/reloaded. It runs until the browser is closed or the extension is removed. It is good practice to put page independent logic/functionality in the background.

To use background files, you need to use the background module.

Code run at page load: "content scripts"

If your extension works with the individual web pages a user sees, you should use content scripts.

For example, an extension which changes a web page so that any long words are replaced with links to that word in an online dictionary.

To use content scripts, you need to use the activations module.

Code run when a button is clicked: "popup code"

You can use the button module to add an icon to the brower toolbar.

The HTML page which may be displayed when a user clicks on this icon can include JavaScript. This JavaScript is executed each time the popup is opened, and is destroyed when the popup is closed; therefore, it is closer conceptually to content scripts than background code.