Version targeting
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In computing, version targeting is a technique that allows a group of (presumably knowledgeable) users (including software developers) utilise some advanced software features that were introduced in a particular software version while allowing users accustomed to the prior versions still utilise the same software as if the new features were never added to the software. It is a way to ensure backwards compatibility when new software features would otherwise break it.
The concept is somewhat similar with DOCTYPE, although the implementation and the intent differs.
In Mozilla Firefox
Version targeting has been used in Mozilla Firefox[1] when it introduced JavaScript 1.6 in Firefox 1.5[2] and JavaScript 1.7 in Firefox 2.0:[3] developers willing to use the new scripting engine had to explicitly opt-in.[1]
Proposed utilisation in Internet Explorer
Version targeting was also a proposed by Microsoft for utilisation in its Internet Explorer 8 product-in-development but the idea was later thrown out of consideration.[4]
The proposal came after the release of Internet Explorer 7 which improved its CSS 2.1 support[5] at the cost of causing some websites that were developed for Internet Explorer 6 to be rendered incorectly when viewed with the new browser version.[6][7]
Microsoft contacted the Web Standards Project and experts on Web standards and asked for assistance in devising a new DOCTYPE-like technique that could work across browsers and let Web developers specify exact browser versions under which their Web sites are known to work correctly, and browsers implementing this form of version targeting would utilise the correct rendering engine versions to display the site correctly[6]
Criticism
The concept of version targeting, especially as proposed by Microsoft, has been criticised for being a new form of browser sniffing and for violating the principle of forward-compatible development where progressive enhancement is preferred.[8]
References
- ^ a b http://www.alistapart.com/articles/minorthreat
- ^ http://developer.mozilla.org/en/New_in_JavaScript_1.6
- ^ http://developer.mozilla.org/en/New_in_JavaScript_1.7#Using_JavaScript_1.7
- ^ http://blogs.msdn.com/ie/archive/2008/03/03/microsoft-s-interoperability-principles-and-ie8.aspx
- ^ http://msdn.microsoft.com/en-us/library/bb250496.aspx
- ^ a b http://www.alistapart.com/articles/beyonddoctype
- ^ http://www.etre.com/blog/2006/10/ie7_were_they_ready/
- ^ http://www.alistapart.com/articles/fromswitchestotargets