jQuery selector :link not working with $.is() or $.filter()...?

It seems like the selector ":link" is not supported by jQuery's filter() 开发者_高级运维or is() function. For instance, if I evaluate $(":link") on a page it returns multiple links. If I evaluate $(":link").filter(":link") or $(":link").is(":link"), an error is thrown. The error message is "Syntax error, unrecognized expression: link".

Is this by design? Do filter() and is() not support the same CSS selectors is jQuery does generally? Is there documentation as to the difference?

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Patrick commented that jQuery defaults in some cases to the browser's built in querySelector or querySelectorAll where it exists. So, :link appears to work on some browsers, but I wouldn't suggest using it as it seems to produce wonderfully bizarre results.

<a href="www.foo.com">Hello</a>

alert($("a").is("a")); // do it this way

// changes the anchor's CSS, but does not return the length
alert($(":link").css('background','yellow').length); 

Demo: ​http://jsfiddle.net/xWPw7/4