Comments on: Commentag plugin now compatible with Prototype.js lib running in parallel http://www.commentag.com/blog/2008/04/21/commentag-plugin-now-compatible-with-prototypejs-lib-running-in-parallel/ Latest news from within CommenTag team Fri, 29 Aug 2008 07:28:47 +0000 http://wordpress.org/?v=2.3.2 By: Xavier http://www.commentag.com/blog/2008/04/21/commentag-plugin-now-compatible-with-prototypejs-lib-running-in-parallel/#comment-144 Xavier Tue, 22 Apr 2008 15:53:40 +0000 http://www.commentag.com/blog/2008/04/21/commentag-plugin-now-compatible-with-prototypejs-lib-running-in-parallel/#comment-144 In fact prototypejs lib extends all arrays with properties which are not set to non-enumerable. That's the reason why all "for ... in" are broken. From the Prototype website http://www.prototypejs.org/api/array By default, the prototype and the length properties are so marked, which prevents you from enumerating over array methods when using for…in. This comfort led developers to use for…in as a shortcut for indexing loops, when it is not its actual purpose. However, Prototype has no way to mark the methods it adds to Array.prototype as non-enumerable. Therefore, using for…in on arrays when using Prototype will enumerate all extended methods as well, such as those coming from the Enumerable module, and those Prototype puts in the Array namespace (described in this section, and listed further below). In fact prototypejs lib extends all arrays with properties which are not set to non-enumerable. That’s the reason why all “for … in” are broken.

From the Prototype website http://www.prototypejs.org/api/array

By default, the prototype and the length properties are so marked, which prevents you from enumerating over array methods when using for…in. This comfort led developers to use for…in as a shortcut for indexing loops, when it is not its actual purpose.

However, Prototype has no way to mark the methods it adds to Array.prototype as non-enumerable. Therefore, using for…in on arrays when using Prototype will enumerate all extended methods as well, such as those coming from the Enumerable module, and those Prototype puts in the Array namespace (described in this section, and listed further below).

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