Extra space with starred version of a DeclarePairedDelimiter command

[evfinkn]

Issue Summary

When using an operator before the starred version of a command made with \DeclarePairedDelimiter (or its variants), an extra space is added between them. This is true in both MathJax v3 and MathJax v4. I would expect this when using scaled delimiters manually, such as in \sin\left(x\right), but the mathtools documentation mentions fixing this:

Within the starred version of \DeclarePairedDelimiter and \DeclarePairedDelimiterX we make a few changes such that the auto scaled \left and \right fences behave as opening and closing fences, i.e. $\sin(x)$ vs. $\sin\left(x\right)$ (the later made via $\sin\left(x\right)$), notice the gap between ‘sin’ and ‘(’.

Technical details:

• MathJax Versions: 3.2.2, 4.0.0-beta.4
• Client OS: macOS 14.3
• Browsers: Obsidian 1.5.3 (which uses Chromium), Firefox 122.0.1

I'm not sure how Obsidian configures and loads MathJax, but for MathJax v4.0.0-beta.4 in Firefox, I'm using the following configuration:

MathJax = {
  loader: { load: ["[tex]/mathtools"] },
  tex: { packages: { "[+]": ["mathtools"] } },
};

and loading MathJax via

<script type="text/javascript" src="https://cdn.jsdelivr.net/npm/mathjax@4.0.0-beta.4/tex-mml-chtml.js"></script>

Supporting information:

The following screenshots show what I'm referring to. I'd expect the brackets on both lines to align, like in LaTeX.

LaTeX:

MathJax v3:

MathJax v4:

And here's the TeX used in those screenshots:

\DeclarePairedDelimiterXPP\Prob[1]{\Pr}[]{}{#1}
\begin{align}
    \text{unstarred:}\qquad & \Prob{A} \Prob{B} \\
    \text{starred:}\qquad & \Prob*{A} \Prob*{B} \\
\end{align}

[dpvc]

Thanks for the report. I will need to look into how best to resolve this.

[dpvc]

OK, I have a solution and will make a PR for it. In the meantime, you can use

MathJax = {
  loader: {load: ['[tex]/mathtools']},
  tex: {packages: {'[+]': ['mathtools']}},
  startup: {
    ready() {
      const ParseUtil = MathJax._.input.tex.ParseUtil.default;
      const {MathtoolsMethods} = MathJax._.input.tex.mathtools.MathtoolsMethods;
      MathtoolsMethods.PairedDelimiters = function PariedDelimiters(
        parser, name, open, close, body = '#1', n = 1, pre = '', post = ''
      ) {
        const star = parser.GetStar();
        const size = (star ? '' : parser.GetBrackets(name));
        const [left, right, after] = (star ? ['\\mathopen{\\left', '\\right', '}\\mathclose{}'] :
                                      size ? [size + 'l' , size + 'r', ''] : ['', '', '']);
        const delim = (star ? '\\middle' : size || '');
        if (n) {
          const args = [];
          for (let i = args.length; i < n; i++) {
            args.push(parser.GetArgument(name));
          }
          pre  = ParseUtil.substituteArgs(parser, args, pre);
          body = ParseUtil.substituteArgs(parser, args, body);
          post = ParseUtil.substituteArgs(parser, args, post);
        }
        body = body.replace(/\\delimsize/g, delim);
        parser.string = [pre, left, open, body, right, close, after, post, parser.string.substring(parser.i)]
          .reduce((s, part) => ParseUtil.addArgs(parser, s, part), '');
        parser.i = 0;
        ParseUtil.checkMaxMacros(parser);
      };

      MathJax.startup.defaultReady();
    }
  }
};

as a work-around until it is fixed.