How to define and use macro in Mathjax? - require

Question

I often use vector operation, and normally vector is written by Bold font, e.g.
$$ \boldsymbol x = \boldsymbol a \times \boldsymbol b + \boldsymbol c $$
which is somehow too long, so I like to define some new commands \bx, \ba, \bb first,
$$
\newcommand{\bx}{\boldsymbol x}
\newcommand{\ba}{\boldsymbol a}
\newcommand{\bb}{\boldsymbol b}
\newcommand{\bc}{\boldsymbol c}
$$
then above equation can be written shortly as:
$$ \bx = \ba \times \bb + \bc $$
Because I use these Bold fonts so often, I don't want to type them time by time, I plan to define them as macro in a file: boldfont.js , when I need to type vector, I just require boldfont.js.
I write file as follows (save the file as: /config/TeX/boldfont.js, other file (such as color.js) under the same directory):
MathJax.Hub.Config({
TeX: {
Macros: {
ba: '{\\boldsymbol a}',
bb: '{\\boldsymbol b}',
bc: '{\\boldsymbol c}',
bd: '{\\boldsymbol d}',
be: '{\\boldsymbol e}',
bf: '{\\boldsymbol f}',
bg: '{\\boldsymbol g}',
bh: '{\\boldsymbol h}',
bi: '{\\boldsymbol i}',
bj: '{\\boldsymbol j}',
bk: '{\\boldsymbol k}',
bl: '{\\boldsymbol l}',
bm: '{\\boldsymbol m}',
bn: '{\\boldsymbol n}',
bo: '{\\boldsymbol o}',
bp: '{\\boldsymbol p}',
bq: '{\\boldsymbol q}',
br: '{\\boldsymbol r}',
bs: '{\\boldsymbol s}',
bt: '{\\boldsymbol t}',
bu: '{\\boldsymbol u}',
bv: '{\\boldsymbol v}',
bw: '{\\boldsymbol w}',
bx: '{\\boldsymbol x}',
by: '{\\boldsymbol y}',
bz: '{\\boldsymbol z}',
}
}
});
And I try to use the file (using \require command) as
$$
\require{boldfont}
\bf=\bu+\bv-\bw
$$
But it doesn't work, what's wrong？ How to define macro and use it?
Help me, please.

Answer 1

The TeX configuration block is read when the TeX input jax is first loaded, so if you call MathJax.Hub.Config() after that, the changes you make will not be seen by the TeX input jax. So any macros you add that way will not have an effect.
Instead you should use
MathJax.InputJax.TeX.Macro('bx', '\\boldsymbol{x}');
MathJax.InputJax.TeX.Macro('ba', '\\boldsymbol{a}');
...
If you have a macro that takes arguments, you can add a third parameter that is the number of arguments needed. E.g.
MathJax.InputJax.TeX.Macro('bs', '\\boldsymbol{#1}', 1);
The file should be stored in the MathJax/extensions/TeX folder (not MathJax/config/TeX), and if you call it boldfont.js, then at the end of the file, you need to add the line
MathJax.Ajax.loadComplete('[MathJax]/extensions/TeX/boldfont.js');
With those changes, I think you should be able to get it to work. If not, check your console log for messages, and also use
MathJax.Message.Log()
to see if there are any file-load failures listed.
(This is my answer from the MathJax User's Forum where this question was cross posted).