unload

The unload module allows modules to register callbacks that are called when they are unloaded. It is similar to the CommonJS module of the same name in the Narwhal platform.

API Reference

Functions

ensure(object, name)

Calling ensure() on an object does two things:

  1. It replaces a destructor method with a wrapper method that will never call the destructor more than once.
  2. It ensures that this wrapper method is called when send() is called.

Therefore, when you register an object with ensure(), you can call its destructor method yourself, you can let it happen for you, or you can do both.

The destructor will be called with a single argument describing the reason for the unload; see when(). If object does not have the expected destructor method, then an exception is thrown when ensure() is called.

object : object

An object that defines a destructor method.

[ name : string ]

Optional name of the destructor method. Default is unload.

when(callback)

Registers a function to be called when send() is called.

callback : function

A function that will be called when send() is called. It is called with a single argument, one of the following strings describing the reason for unload: "uninstall", "disable", "shutdown", "upgrade", or "downgrade". (On Gecko 1.9.2-based applications such as Firefox 3.6, "upgrade" and "downgrade" are not available, and "shutdown" will be sent in their place.) If a reason could not be determined, undefined will be passed instead. Note that if an add-on is unloaded with reason "disable", it will not be notified about "uninstall" while it is disabled. A solution to this issue is being investigated; see bug 571049.

send(reason)

Sends an "unload signal", thereby triggering all callbacks registered via when(). In general, this function need not be manually called; it is automatically triggered by the embedder.

[ reason : string ]

An optional string describing the reason for unload; see unload.when().