Listen for Page Load

We are planning to deprecate the use by Firefox add-ons of the techniques described in this document.

Don't use these techniques to develop new add-ons. Use WebExtensions instead.

If you maintain an add-on which uses the techniques described here, consider migrating it to use WebExtensions instead.

Add-ons developed using these techniques might not work with multiprocess Firefox (e10s), which is already the default in Firefox Nightly and Firefox Developer Edition, and will soon be the default in Beta and Release versions of Firefox. We have documentation on making your add-ons multiprocess-compatible, but it will be more future-proof for you to migrate to WebExtensions.

A wiki page containing resources, migration paths, office hours, and more, is available to help developers transition to the new technologies.

To follow this tutorial you'll need to have learned the basics of jpm.

You can get notifications about new pages loading using the tabs module. The following add-on listens to the tab's built-in ready event and just logs the URL of each tab as the user loads it:

require("sdk/tabs").on("ready", logURL);
function logURL(tab) {

You will find this console output in the Browser Console, not the Web Console.

You don't get direct access to any content hosted in the tab.

To access tab content you need to attach a script to the tab using tab.attach(). This add-on attaches a script to all open tabs. The script adds a red border to the tab's document:

require("sdk/tabs").on("ready", runScript);
function runScript(tab) {
    contentScript: "if (document.body) = '5px solid red';"

(This example is only to show the idea: to implement something like this, you should instead use page-mod, and specify "*" as the match-pattern.)

Learning More

To learn more about working with tabs in the SDK, see the tabs API reference. You can listen for a number of other tab events, including open, close, and activate.

To learn more about running scripts in tabs, see the tutorial on using tab.attach().

Document Tags and Contributors

 Contributors to this page: wbamberg, groovecoder, hgezim, tomica
 Last updated by: wbamberg,