The color extension defines the \color macro as in the LaTeX color package, along with \colorbox, \fcolorbox, and \definecolor. It declares the standard set of colors (Apricot, Aquamarine, Bittersweet, and so on), and provides the RGB, rgb, and grey-scale color spaces in addition to named colors.

This extension is loaded automatically when the autoload extension is used. To load the color extension explicitly, add '[tex]/color' to the load array of the loader block of your MathJax configuration, and add 'color' to the packages array of the tex block.

window.MathJax = {
  loader: {load: ['[tex]/color']},
  tex: {packages: {'[+]': ['color']}}

Alternatively, use \require{color} in a TeX expression to load it dynamically from within the math on the page, if the require extension is loaded.


In version 2, a non-standard \color macro was the default implementation, but in version 3, the standard LaTeX one is now the default. The difference between the two is that the standard \color macro is a switch (everything that follows it is in the new color), whereas the non-standard version 2 \color macro takes an argument that is the mathematics to be colored. That is, in version 2, you would do

\color{red}{x} + \color{blue}{y}

to get a red x added to a blue y. But in version 3 (and in LaTeX itself), you would do

{\color{red} x} + {\color{blue} y}

If you want the old version 2 behavior, use the colorV2 extension instead.