Comments on: How to make a singleton in javascript

By: NFL picks against the spread

NFL picks against the spread — Thu, 13 Oct 2011 12:21:43 +0000

2011…

I do agree with all the ideas you’ve presented in your post. They are very convincing and will certainly work. Still, the posts are too short for beginners. Could you please extend them a little from next time? Thanks for the post….

By: dYcxcgcvfgg

dYcxcgcvfgg — Sun, 09 Oct 2011 03:25:11 +0000

2011…

It’s really a nice and useful piece of info. I’m glad that you shared this helpful info with us. Please keep us up to date like this. Thanks for sharing….

By: dYcxcgcvf

dYcxcgcvf — Sat, 08 Oct 2011 02:07:31 +0000

2011…

It’s really a great and helpful piece of info. I’m glad that you shared this helpful info with us. Please keep us informed like this. Thanks for sharing….

By: Cool New Gadgets

Cool New Gadgets — Tue, 15 Mar 2011 19:57:32 +0000

Ahh,, just following your instruction.. hope to implement it right away.

By: josh09

josh09 — Sun, 29 Nov 2009 03:04:09 +0000

great lesson, I needed it

By: How to write a singleton class in javascript | Javascript Kata

How to write a singleton class in javascript | Javascript Kata — Wed, 30 Sep 2009 12:59:57 +0000

[...] I look at my stats, a lot of people are wondering how to write a singleton class. I already wrote about it before but my old solution exposed the instance of the class so more than one instance could be created [...]

By: Phil

Phil — Fri, 10 Apr 2009 16:04:57 +0000

Hi! I’ve read all your posts and I’m very glad of this discussion. I wonna give something back to all readers and posters in describing a small scenario, where singleton is more than just OOP-Global, and wonna show you, why I think that choosing the right singleton implementation is very important.

I’m deloping a huge project including a JS-Framework. Therefore it’s necessary to inherit classes. So imagine the following example:

We have a class Container and a inherited class FullFadeWindow. The Container-Class represents a Container-Widget that can be instantiated many times and that can contain data loaded per AJAX. The FullFadeWindow is a special window: its always on top and its covering the full screen (or browser window). So I want FullFadeWindow to be a singleton class, inheriting from Container, that is no singleton class.

This can’t be done using a pure static implementation (like Dan’s Log-Example), because of the prototype inheritance. Also the closures-solutions cannot be used this way, because all functions need to be declared in a local context which make prototype inheritance impossible. And because I cannot guarantee that nobody calls my constructor, if I’m using Dan’s first idea, the remaining possibility is MadKat’s one above. This way, we can simple make an existing class to a singleton one, we can use prototype inheritance, and we do not need to “milk” JS to brutally make this object based language to an complete object oriented one.

In addition, the way described in http://kaijaeger.com/articles/the-singleton-design-pattern-in-javascript.html (posted by Antony above) is also not usable in this scenario.

So, if you plan to use prototype inheritance (you know, like X.prototype = new Y()), you should consider MadKat’s solution.

Have fun,
Phil

By: Antony S

Antony S — Fri, 13 Mar 2009 05:28:04 +0000

A very good and simple article on singleton in JS.

http://kaijaeger.com/articles/the-singleton-design-pattern-in-javascript.html

By: Dan

Dan — Sun, 22 Feb 2009 18:33:59 +0000

@zoips @jb
I really like your alternatives. I’ll write a new article with that. Thanks a lot.

By: jb

jb — Sun, 22 Feb 2009 17:54:58 +0000

well a very simple way of having singleton is this
Test= function(){
if(!Test.prototype.instance)
Test.prototype.instance=this;
else
return Test.prototype.instance;
}