cfx
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programmatically use cfx with node.js
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<!-- This Source Code Form is subject to the terms of the Mozilla Public
- License, v. 2.0. If a copy of the MPL was not distributed with this
- file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
<!-- contributed by Atul Varma [atul@mozilla.com] -->
<!-- contributed by Drew Willcoxon [adw@mozilla.com] -->
<!-- edited by Noelle Murata [fiveinchpixie@gmail.com] -->
The `unload` module allows modules to register callbacks that are called
when they are unloaded.
<api name="ensure">
@function
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 the object's module is
unloaded.
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.
@param object {object}
An object that defines a destructor method.
@param [name] {string}
Optional name of the destructor method. Default is `unload`.
</api>
<api name="when">
@function
Registers a function to be called when the module is unloaded.
@param callback {function}
A function that will be called when the module is unloaded. It is called
with a single argument, one of the following strings describing the reason
for unload: `"uninstall"`, `"disable"`, `"shutdown"`, `"upgrade"`, or
`"downgrade"`. 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. See
[bug 571049](https://bugzilla.mozilla.org/show_bug.cgi?id=571049).
</api>