Logging to console from Firefox extension?

Question

I understand that I can log to the console when using a Firefox extension with the cfx run command.

Is there a way to log to a console after the extension has been packaged with cfx xpi? Logging to Firebug is fine if possible.

I have found two blog posts about this (here and here). Both are rather old and don't work any more.

I'm using version 1.10 of the add-on SDK and FF15.

Answer 1

You need to do 2 things:

1. enable logging for addons

• in about:config, add a new option extensions.sdk.console.logLevel and give it the value "all"

• restart Firefox

2. in Firefox open the Browser Console:

• Tools -> Web developer -> Browser console

• NOTE: this is different from the usual Web Console used to debug web pages

You should see addons logs there now.

Answer 2

TLDR:

1. Go to about:config url and create key extensions.sdk.console.logLevel with value all
2. See log messages either in Browser console (Ctrl+Shift+J) or in terminal you started Firefox from.

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cfx or its successor jpm creates this configuration key automatically in development firefox profile.

From logging documentation:

extensions.sdk.console.logLevel: if set, this determines the logging level for all installed SDK-based add-ons.

extensions.extensionID.sdk.console.logLevel, where extensionID is an add-on's Program ID. If set, this determines the logging level for the specified add-on. This overrides the global preference if both preferences are set.