Comments on: Singletons in JavaScript http://www.ashita.org/singletons-in-javascript/ Mon, 19 Dec 2011 08:17:01 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Jonathan Fingland http://www.ashita.org/singletons-in-javascript/comment-page-1/#comment-141 Jonathan Fingland Sat, 05 Dec 2009 05:45:07 +0000 http://ashita.org/?p=329#comment-141 @peter I really wish there were. The problem is this: You can't make an object un-instantiable as there are no private constructors -- just prototypes. You can control scope somewhat, and that's what I've done above. By nesting your constructor inside another function, the global scope doesn't have visibility of the constructor. And if scripts can't see it, then they can't instantiate it. However, if scripts can't see it, then they also can't verify what it is -- hence why instanceof fails. The one option that might work is to create a constructor function that throws an exception if it has already been instantiated before. In fact, I'll add that to the post above. @peter
I really wish there were. The problem is this: You can’t make an object un-instantiable as there are no private constructors — just prototypes. You can control scope somewhat, and that’s what I’ve done above. By nesting your constructor inside another function, the global scope doesn’t have visibility of the constructor. And if scripts can’t see it, then they can’t instantiate it. However, if scripts can’t see it, then they also can’t verify what it is — hence why instanceof fails.

The one option that might work is to create a constructor function that throws an exception if it has already been instantiated before. In fact, I’ll add that to the post above.

]]> By: Peter Robinett http://www.ashita.org/singletons-in-javascript/comment-page-1/#comment-139 Peter Robinett Sat, 05 Dec 2009 00:35:40 +0000 http://ashita.org/?p=329#comment-139 Hi Jonathan, Is there a way to avoid those invalid instanceof operand errors? I've got some code I can't easily change and would like to be able to use instanceof. Thanks, Peter Robinett Hi Jonathan,

Is there a way to avoid those invalid instanceof operand errors? I’ve got some code I can’t easily change and would like to be able to use instanceof.

Thanks,
Peter Robinett

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