How do you confirm which version of MathJax is used when loaded from a CDN?

Question

I have loaded MathJax by putting into the header of an HTML file,

<script type="text/javascript"
  src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML">
</script>

It clearly seems to be loading the "latest" version. However, when I google what the latest version is, it's 3.x. However, when I try to use a function that is in 3.x which is not in 2.x, MathJax.typeset(), I get an error that this is not recognized.

When I try to pop open a developer console and enter MathJax --version it doesn't recognize this. So how can I confirm which version is being loaded into the page?

Answer 1

If you open the URL

https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML

in a browser, you get Javascript code which contains the following lines

(function () {
  var newMathJax = 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js';
  var oldMathJax = 'cdn.mathjax.org/mathjax/latest/MathJax.js';
...

//
//  Issue a console warning
//
console.warn('WARNING: cdn.mathjax.org has been retired. 
Check https://www.mathjax.org/cdn-shutting-down/ for migration tips.')

So, you might want to have a look at

https://www.mathjax.org/cdn-shutting-down

Upgrade from v2 to v3 is described in

https://docs.mathjax.org/en/v3.2-latest/upgrading/v2.html