Support array environment's vertical positioning optional argument

[ghost]

This is a question about the optional vertical positioning argument of an array. When I tried
\begin{array}[t]{c|}1\\ \,\end{array} \begin{array}[t]{rrrr}1& 2& -5& 2\\ & 1& 3& -2\\ \hline 1& 3& -2& 0\end{array}
I did not get an error message and it seems to work, but I did not find the [position] optional argument mentioned in the official documentation. Can I assume that it is officially supported?

[kevinbarabash]

It looks like it isn't supported yet. I get the following error message when trying your example on katex.org I get the follow error:

KaTeX parse error: Unknown column alignment: [ at position 14: \begin{array}[̲t]{c|}1\\ \,\en…

Which version are you using?

[ghost]

I am not sure about the version (I will ask). I am entering math expressions to an online platform where they use KaTeX to display the formulas.
Here is a screenshot of the editor platform with the rendered arrays properly aligned at the top row.

[pzinn]

I'm surprised this hasn't been addressed yet. \begin{array} is a really basic command, and its optional argument (b or t for bottom or top alignment) shouldn't be hard to implement.