Components object 编辑

Non-standard
This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

Warning: This object is only intended for code running with chrome privileges. Exposing the object to regular web code was a mistake. If you use this object on your web page, your site might break at any time! In current versions of Firefox only a few interfaces required for compatibility are still accessible. Don't use Components!

The Components object is the object through which XPConnect functionality is reflected into JavaScript. The Components object is actually a native instance of the nsIXPCComponents interface which is reflected into JavaScript as a top level object using XPConnect.

Some properties of Components require advanced privileges and may not work in web pages.

The Components object has the following members:

classes

array of classes by ContractID

classesByID

array of classes by CID

Constructor

constructor for constructor of components

Exception

constructor for XPConnect exceptions

ID

constructor for XPCOM nsIDs

interfaces

array of interfaces by interface name

interfacesByID

array of interfaces by IID

isSuccessCode

function to determine if a given result code is a success code

lastResult

result code of most recent XPConnect call

manager

the global XPCOM component manager

results

array of known result codes by name

returnCode

pending result for current call

stack

current JavaScript call stack

utils

provides access to several useful features

utils.atline

Provides access to the value of the atline property in the JavaScript environment.

utils.createObjectIn

Creates a new object in the scope of the specified object's compartment. May only be called from JavaScript code.

utils.evalInSandbox

Runs JavaScript code in a sandbox, usually used to run code with restricted privileges.

utils.forceGC

Forces a garbage collection cycle.

utils.getGlobalForObject 

Returns the global object with which a given object is associated (through its prototype chain at birth, for example).

utils.getWeakReference 

Gets a weak reference for the object passed in.

utils.import 

Loads a JavaScript module into the current script, without sharing a scope.

utils.lookupMethod

Looks up a native (i.e. declared in the interface) method or property of an XPCOM object. Serves the same purpose as XPCNativeWrapper.

utils.makeObjectPropsNormal

Ensures that all functions come from the specified object's scope, and aren't cross-compartment wrappers. May only be called from JavaScript code.

utils.methodjit Obsolete since Gecko 24.0

Provides access to the value of the methodjit property in the JavaScript environment.

utils.methodjit_always Obsolete since Gecko 24.0

Provides access to the value of the methodjit_always property in the JavaScript environment.

utils.relimit

Provides access to the value of the relimit property in the JavaScript environment.

utils.reportError

Reports a JavaScript Error object to the Error Console.

utils.schedulePreciseGC

Requests that garbage collection occur sometime in the future when no JavaScript code is running; accepts a callback function to receive notification once collection is complete.

utils.setGCZeal()

Sets the GC zeal level for the context.

utils.strict

Provides access to the value of the strict property in the JavaScript environment.

utils.werror

Provides access to the value of the werror property in the JavaScript environment.

utils.Sandbox

Creates sandbox objects for use with evalInSandbox.

utils.xml

Provides access to the value of the xml property in the JavaScript environment.