# Why does not the current version of MathJax support \delimiterfactor?

How to verify, which version of MathJax is used here? It seems that v. 2.5 is not implemented yet. It has very useful features, as \delimiterfactor, which is needed here: https://tex.stackexchange.com/questions/284809/getting-large-braces-in-mathjax

1. Right-click any formula, like this one: $\int_0^1 e^x\,dx$