# How to label equations on the left with mathjax?

In a proper TeX environment, one can use preamble to set the equation labels (tags) on the left for the entire document. There are also tricks to do this locally.

On the webpage here, sometimes a tag on the right end seems too far. (I'm a two-column person)

Is it possible in Math StackExchange (using mathjax or alternatives) to label text or equations on the left, at the beginning of a line?

The point is that the labels should properly work as hyperlinks, jumping to the place you want to show. That is, lists or itemize is no good for this purpose.

Another motivation for this is that: if such method exists, it can also be useful as a work-around for section/paragraph labeling within a single post, which I gather is not possible with mathjax.

I tried to require the TeX hyperref or similar packages, but so far I cannot figure out the correct syntax. I also considered phantom-like labels like \tag*{$\color{white}{__some text__}$} to push the label around. Of course this doesn't work.

I don't know any java and I have limited skills in html, but I'm open to anything that works on this site (and isn't disruptive to the system).

P.S.

I'm not talking about left-aligning an equation like what this post addresses. However, if this can be made into a left-tag trick, I'd love to know.

• You are probably aware of this, but I'll mention that this question and this answer discuss how to use tag + label to get the links. However, unless I missed something, they do not mention how to get them on the left. – Martin Sleziak Apr 3 '18 at 7:06
• @MartinSleziak Yes, I am aware of that. Thanks for the reminder. Another attempt I tried with this hyperlink mechanism is to put \tag in difference places in array or align relative to multiple &. The tag still appears on the far right. – Lee David Chung Lin Apr 3 '18 at 7:15
• This can be done but only via the MathJax configuration, i.e. on a site level, cf. docs.mathjax.org/en/latest/options/input-processors/TeX.html – Peter Krautzberger Apr 3 '18 at 9:26
• @PeterKrautzberger Thank you for the valuable information. Would you mind posting this as an answer? If no other trickery or 'scripts' involving java or html show up after a while, I'll accept your answer to conclude this post. – Lee David Chung Lin Apr 4 '18 at 8:45

Generally speaking, this can be done. However, it's only possible by changing the MathJax configuration (cf. TagSide in the TeX input processor options).
• Reading the OP again, you could hack around using negative hspace but that seems bad. Better to add an id via \cssId (maybe with additional styling) to be able to reference that specific part in links later on. – Peter Krautzberger Apr 6 '18 at 11:09
I have used \tag{1}\label{1} and then referred to it with \eqref{1} and \ref{1}. The \tag puts the visual cue, while the \label puts the hyper reference.