Migration Guide

v0.18.0

KaTeX's internal CSS classes are now prefixed with katex-. If you apply custom styles or maintain allowlists (for example, in a content sanitizer) that target KaTeX's internal classes, you must update your selectors. The list of renamed classes is:

Before	After
`.accent`	`.katex-accent`
`.base`	`.katex-base`
`.fix`	`.katex-fix`
`.hdashline`	`.katex-hdashline`
`.hline`	`.katex-hline`
`.inner`	`.katex-inner`
`.newline`	`.katex-newline`
`.overlay`	`.katex-overlay`
`.overline`	`.katex-overline`
`.root`	`.katex-root`
`.rule`	`.katex-rule`
`.sizing`	`.katex-sizing`
`.smash`	`.katex-smash`
`.sout`	`.katex-sout`
`.stretchy`	`.katex-stretchy`
`.strut`	`.katex-strut`
`.tag`	`.katex-tag`
`.thinbox`	`.katex-thinbox`
`.underline`	`.katex-underline`
`.vbox`	`.katex-vbox`

v0.17.0

The internal API for __defineFunction changed: properties should no longer be wrapped in props. Move the members of props up to the top level of the definition object. For example:

// Before
katex.__defineFunction({
    type: "overline",
    names: ["\\overline"],
    props: {
        numArgs: 1,
    },
    handler(context, args) { /* ... */ },
});

// After
katex.__defineFunction({
    type: "overline",
    names: ["\\overline"],
    numArgs: 1,
    handler(context, args) { /* ... */ },
});

v0.16.0

The copy-tex extension no longer has (or requires) a CSS file. Remove any import of copy-tex.css, such as require('katex/dist/contrib/copy-tex.css') or <link>s to it.

v0.15.0

\relax is now implemented as a function. It'll stop expansions and parsing, so the behavior around \relax may change. For example, \kern2\relax em will no longer work.

v0.14.0

With module loaders that support conditional exports and ECMAScript modules, import katex from 'katex'; will import the ECMAScript module.

You can now use:

Before	After
`require('katex/dist/contrib/[name].js')`	`require('katex/contrib/[name]')`
`import katex from 'katex/dist/katex.mjs'`	`import katex from 'katex'`
`import 'katex/dist/contrib/[name].mjs'`	`import 'katex/contrib/[name]'`

v0.13.0

Macro arguments

Tokens will not be expanded while parsing a macro argument. For example, \frac\foo\foo, where the \foo is defined as 12, will be parsed as \frac{12}{12}, not \frac{1}{2}12. To expand the argument before parsing, \expandafter can be used like \expandafter\frac\foo\foo.

`\def`

\def no longer accepts a control sequence enclosed in braces. For example, \def{\foo}{} no longer works and should be changed to \def\foo{}.

It also no longer accepts replacement text not enclosed in braces. For example, \def\foo1 no longer works and should be changed to \def\foo{1}.

`\newline` and `\cr`

\newline and \cr no longer takes an optional size argument. To specify vertical spacing, \\ should be used.

`\cfrac`, `\color`, `\textcolor`, `\colorbox`, `\fcolorbox`

They are no longer allowed as an argument to primitive commands, such as \sqrt (without the optional argument) and super/subscript. For example, \sqrt\textcolor{red}{x} no longer works and should be changed to \sqrt{\textcolor{red}{x}}.