It has been gamed in the past. For example, http://delphi.org/2008/10/the-many-faces-of-delphi/ and http://delphi.org/2008/10/delphi-keeps-climbing/
There have been other blips in the past caused by documentation for a project getting moved to a different server and in doing so the SEO for the material (inadvertently) changed.
TIOBE measures the SEO for different programming languages, nothing more.
Outside of the tech bubble it's believable that JavaScript isn't as popular.
Javascript is useful for websites. And outside of the tech bubble, that's basically all it's good for.
Yes, you can use Javascript for non-website stuff. But nobody is doing that because there are many cheaper and more efficient languages out there for doing all that other stuff.
I can only imagine there's a ton of massive ASP.NET MVC + a bit of jQuery internal apps still chugging along too
It is an interesting metric, but I just can't bring myself to see it as the measure of popularity that it is presented as. The number of page hits for a language is a function of many things. Popularity is one. Others include age, complexity, and how confusing/difficult-to-learn the language or its libraries are. I'm guessing there's a marketability angle, too - for economic reasons, there may not be as many codepoints being poured onto languages whose users are less likely to purchase commercial tools or consulting services.
I can think of no better illustration of this than the 5th, 6th and 7th places in this month's rankings. Does anyone really believe that JavaScript is only the 7th most popular programming language these days? Does anyone really believe that both C# and Visual Basic are more popular than JavaScript? If you take the TIOBE score as just a measure of popularity, it would seem to suggest that .NET developers are collectively over 3 times as numerous as JavaScript developers.