getVersion - Web APIs 编辑

Parts of this page show the use of the XPInstall API. The majority of this API is now deprecated and as of Gecko 1.9 no longer available. Extension, Theme, and plug-in developers must switch away from install.js based packages to the new packaging scheme with an install.rdf manifest. In particular plugin developers should see how to package a plugin as an extension.

getVersion

Returns an object representing the version number from the Client Version Registry for the specified component. It is used in both trigger scripts and installation scripts.

Method of

InstallTrigger object

Syntax

InstallVersion getVersion ( String component );

Parameters

The getVersion method has one parameter:

component

The name of a component in the Client Version Registry.

Returns

If Software Installation is disabled, this method returns NULL. Otherwise, it returns an InstallVersion object representing the version of the component.

If the component has not been registered in the Client Version Registry or if the specified component was installed with a null version, this method returns null.

Installing a component with a NULL version indicates that the component should always be updated when the opportunity arises.