i dont know about the that code, but this is what i use, which works okay

function externalLinks(){if(!document.getElementsByTagName){return;}var anchors=document.getElementsByTagName("a");for(var i=0;i<anchors.length;i++){var anchor=anchors[i];if(anchor.getAttribute("href")&&(anchor.getAttribute("rel")=="external"||anchor.getAttribute("rel")=="external nofollow"||anchor.getAttribute("rel")=="nofollow external")){anchor.target="_blank";}}}
externalLinks();

this is what you would use for the links...

<a href="blah" rel="external">

or

<a href="blah" rel="nofollow external">

or

<a href="blah" rel="external nofollow">

any of those will open in a new window

i did what you suggested and still no luck? :( take a look at the code, is there something i've done wrong?

since W3C has 'dropped' the target='_blank' attribute

Says who where? I thought that whole issue was settled years ago.

A valid browsing context name or keyword is any string that is either a valid browsing context name or that is an ASCII case-insensitive match for one of: _blank, _self, _parent, or _top.

b/w

User agent implementors are encouraged to provide a way for users to configure the user agent to always reuse the current browsing context.

Nice :) Browsers should recognize it, but they should also enable users to override it.

since W3C has 'dropped' the target='_blank' attribute

Says who where? I thought that whole issue was settled years ago.

It was deprecated in HTML 4.01. Looking at the HTML 4.01 Strict DTD [w3.org] you'll find that it's missing from the <!ATTLIST A ...> section. The HTML 4.01 Transitional DTD [w3.org] includes it because the Transitional DTD includes deprecated elements and attributes.
In HTML5 it is no longer deprecated.
With that said, though, there are still good usability arguments to be made for not using it (and of course, there are also some valid cases for using it as well).

The javascript just adds it back in, so anybody wanting to avoid using it: it's pointless to try it via that javascript. Something that would call window.open() would be a different story.

But the main point is that while it's frowned upon in the old html4, it's valid in (x)html5, and hence it's valid as long as you use the current html version.

The (x)html5 references:
Target on an <a> element: [w3.org...]
Valid browsing contexts (the value for target=): [w3.org...]

Usability: I have strong doubts on using it, esp when you see the high percentage of users on mobile devices nowadays ...