Can you check if an object is wrapped by XPConnect (Firefox)?
My scenario: I am iterating over the window object and trying to retrieve only user-defined variables/functions and filtering out native browser objects.
for(var i in window) {
// Right now I just have a bunch of if checks on window[i]
}
I noticed that native browser objects/XPCOM components are wrapped via XPConnect which returns a wrapper of the object that allows it to interface with Javascript. I am thinking that if I could somehow check and see if the object is a wrapper then I can filter it out. 开发者_如何学CIs there a way to check if an object is wrapped via XPConnect? I would like to filter out all objects that are wrapped as any of the wrapper types listed here: https://developer.mozilla.org/en/XPConnect_wrappers
You can detect an XPCWrappedNative because x instanceof Components.interfaces.nsISupports
returns true. However, this also returns true for DOM nodes, documents, windows etc. If this isn't what you want, a subsequent x.QueryInterface(Components.interfaces.nsIClassInfo)
should succeed for most DOM objects.
You can't detect an XPCWrappedJS unless the underlying JS object exposes the wrappedJSObject property. (You don't actually see the XPCWrappedJS object itself, since that's a C++ object, but that object could then get passed back into JS as an XPCWrappedNative.)
You can detect an XPCNativeWrapper using x == XPCNativeWrapper(x)
. The underlying object will itself be an XPCWrappedNative, of course.
You can't really detect an XPCSafeJSObjectWrapper, you just have to know that if you unwrap an XPCNativeWrapper for a content object then you will get an XPCSafeJSObjectWrapper.
Why not just check for the existence of a property named wrappedJSObject
which wrapped objects expose? If it quacks like a duck...
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