When doing practical math, you often fork your calculation due to some conditions, eg. when doing equations with absolute value.
There is a symbol for this, and I wonder if mathJax can render this one or not. And if it can, I'd like to know the command.
Here is an image of what I mean:
The amsmath package provides the cases environment:
\documentclass{article}
\usepackage{amsmath}
\begin{document}
$f(x) = \begin{cases} x^{2} \sin \left( \frac{1}{x}\right) & \text{if } x\neq 0 \\
0 & \text{if } x=0 %
\end{cases}$
\end{document}
\begin{cases}from amsmath package (mathjax also supports this)casesenvironment fromamsmath. I have no idea whether or not this would work with MathJaX since although MathJaX's syntax is based on LaTeX, MathJaX does not use TeX itself. In fact, pure MathJaX questions are off-topic on this site. You could ask "I want to do this in MathJaX, I know that MJ is based on LaTeX. How do I do this in LaTeX so I know what to try in MJ?". That might keep it on-topic.casesenvironment (requiresamsmath}. see, for example, Alignment in cases and How to write conditional equations with one-sided curly bracketscasesenvironment.