I want that a key that is only applied in specific slides/frames just like uncover or only. Here's an example:
\documentclass{beamer}
\usepackage{tikz}
\begin{document}
\begin{frame}
\begin{tikzpicture}
\draw [fill=orange] (0,0) rectangle (1,1);
\uncover<1>{\node at (2,0) [anchor=west] {1};}
\uncover<2>{\node at (2,0) [anchor=west] {2 -- should be only orange here};}
\uncover<3>{\node at (2,0) [anchor=west] {3};}
\end{tikzpicture}
\end{frame}
\end{document}
The output looks like this:

Problem
I want for example that the fill key is only applied to the second frame - something like this: fill=<2>orange.
I tried to understand this related question but the code of the accepted answer is too complicated for me. But I guess it has something to do with it.
Any ideas?

\onlyis not a valid TikZ key; defining the style solves the problem, as now theonslidestyle is a valid key. – Gonzalo Medina Feb 09 '14 at 17:17.code args, the definition you put in is actually (nearly) arbitrary LaTeX code, and thus you can use\onlythere. But the stuff you put in square brackets following\drawcannot just be anything. It has to be the name of a style. (A PGF key, technically.) – David Z Feb 10 '14 at 03:22