Options

You can provide an object of options as the last argument to katex.render and katex.renderToString. Available options are:

  • displayMode: boolean (default: false). If true the math will be rendered in display mode. If false the math will be rendered in inline mode. Differences between the two modes include:

    • Display mode starts in \displaystyle, so \int and \sum are large, for example; while inline mode starts in \textstyle, where subscripts and superscripts usually don't stack on top of operators like \sum. You can always manually switch between \displaystyle and \textstyle using those commands.
    • Display mode centers math on its own line and disables automatic line breaking (though you can customize this behavior with custom CSS). In inline mode, KaTeX allows line breaks after outermost relations (like = or <) or binary operators (like + or \times), the same as TeX.

  • output: string. Determines the markup language of the output. The valid choices are:

    • html: Outputs KaTeX in HTML only.
    • mathml: Outputs KaTeX in MathML only.
    • htmlAndMathml: Outputs HTML for visual rendering and includes MathML for accessibility. This is the default.

  • leqno: boolean. If true, display math has \tags rendered on the left instead of the right, like \usepackage[leqno]{amsmath} in LaTeX.

  • fleqn: boolean. If true, display math renders flush left with a 2em left margin, like \documentclass[fleqn] in LaTeX with the amsmath package.

  • throwOnError: boolean. If true (the default), KaTeX will throw a ParseError when it encounters an unsupported command or invalid LaTeX. If false, KaTeX will render unsupported commands as text, and render invalid LaTeX as its source code with hover text giving the error, in the color given by errorColor.

  • errorColor: string. A color string given in the format "#XXX" or "#XXXXXX". This option determines the color that unsupported commands and invalid LaTeX are rendered in when throwOnError is set to false. (default: #cc0000)

  • macros: object. A collection of custom macros.

    • Each macro is a key-value pair where the key is a new command name and the value is the expansion of the macro.
    • Example: macros: {"\\R": "\\mathbb{R}"}
    • More precisely, each property of macros can have a name that starts with a backslash like "\\foo" (defining command \foo) or is a single character like "α" (defining the equivalent of a TeX active character), and a value that is one of the following:
      • A string with the LaTeX expansion of the macro (which will be recursively expanded when used). The string can invoke (required) arguments via #1, #2, etc.
      • A function that accepts an instance of MacroExpander as first argument and returns the expansion as a string. MacroExpander is an internal API and subject to non-backwards compatible changes. See src/defineMacro.js for its usage.
      • An expansion object matching an internal MacroExpansion specification, which is what results from global \def or \let. For example, you can simulate the effect of \let\realint=\int via {"\\realint": {tokens: [{text: "\\int", noexpand: true}], numArgs: 0}}.
    • This object will be modified if the LaTeX code defines its own macros via \gdef or \global\let (or via \def or \newcommand or \let when using globalGroup). This enables consecutive calls to KaTeX to share state (in particular, user macro definitions) if you pass in the same macros object each time.

  • minRuleThickness: number. Specifies a minimum thickness, in ems, for fraction lines, \sqrt top lines, {array} vertical lines, \hline, \hdashline, \underline, \overline, and the borders of \fbox, \boxed, and \fcolorbox. The usual value for these items is 0.04, so for minRuleThickness to be effective it should probably take a value slightly above 0.04, say 0.05 or 0.06. Negative values will be ignored.

  • colorIsTextColor: boolean. In early versions of both KaTeX (<0.8.0) and MathJax, the \color function expected the content to be a function argument, as in \color{blue}{hello}. In current KaTeX, \color is a switch, as in \color{blue} hello. This matches LaTeX behavior. If you want the old \color behavior, set option colorIsTextColor to true.

  • maxSize: number. All user-specified sizes, e.g. in \rule{500em}{500em}, will be capped to maxSize ems. If set to Infinity (the default), users can make elements and spaces arbitrarily large.

  • maxExpand: number. Limit the number of macro expansions to the specified number, to prevent e.g. infinite macro loops. \edef expansion counts all expanded tokens. If set to Infinity, the macro expander will try to fully expand as in LaTeX. (default: 1000)

  • strict: boolean or string or function (default: "warn"). If false or "ignore", allow features that make writing LaTeX convenient but are not actually supported by (Xe)LaTeX (similar to MathJax). If true or "error" (LaTeX faithfulness mode), throw an error for any such transgressions. If "warn" (the default), warn about such behavior via console.warn. Provide a custom function handler(errorCode, errorMsg, token) to customize behavior depending on the type of transgression (summarized by the string code errorCode and detailed in errorMsg); this function can also return "ignore", "error", or "warn" to use a built-in behavior. A list of such features and their errorCodes:

    • "unknownSymbol": Use of unknown Unicode symbol, which will likely also lead to warnings about missing character metrics, and layouts may be incorrect (especially in terms of vertical heights).
    • "unicodeTextInMathMode": Use of Unicode text characters in math mode.
    • "mathVsTextUnits": Mismatch of math vs. text commands and units/mode.
    • "commentAtEnd": Use of % comment without a terminating newline. LaTeX would thereby comment out the end of math mode (e.g. $), causing an error.
    • "htmlExtension": Use of HTML extension (\html-prefixed) commands, which are provided for HTML manipulation.

    A second category of errorCodes never throw errors, but their strictness affects the behavior of KaTeX:

    • "newLineInDisplayMode": Use of \\ or \newline in display mode (outside an array/tabular environment). In strict mode, no line break results, as in LaTeX.

  • trust: boolean or function (default: false). If false (do not trust input), prevent any commands like \includegraphics that could enable adverse behavior, rendering them instead in errorColor. If true (trust input), allow all such commands. Provide a custom function handler(context) to customize behavior depending on the context (command, arguments e.g. a URL, etc.). A list of possible contexts:

    • {command: "\\url", url, protocol} where protocol is a lowercased string like "http" or "https" that appears before a colon, or "_relative" for relative URLs.
    • {command: "\\href", url, protocol}
    • {command: "\\includegraphics", url, protocol}
    • {command: "\\htmlClass", class}
    • {command: "\\htmlId", id}
    • {command: "\\htmlStyle", style}
    • {command: "\\htmlData", attributes}

    Here are some sample trust settings:

    • Forbid specific command: trust: (context) => context.command !== '\\includegraphics'
    • Allow specific command: trust: (context) => context.command === '\\url'
    • Allow multiple specific commands: trust: (context) => ['\\url', '\\href'].includes(context.command)
    • Allow all commands with a specific protocol: trust: (context) => context.protocol === 'http'
    • Allow all commands with specific protocols: trust: (context) => ['http', 'https', '_relative'].includes(context.protocol)
    • Allow all commands but forbid specific protocol: trust: (context) => context.protocol !== 'file'
    • Allow certain commands with specific protocols: trust: (context) => ['\\url', '\\href'].includes(context.command) && ['http', 'https', '_relative'].includes(context.protocol)

  • globalGroup: boolean (default: false). Run KaTeX code in the global group. As a consequence, macros defined at the top level by \def and \newcommand are added to the macros argument and can be used in subsequent render calls. In LaTeX, constructs such as \begin{equation} and $$ create a local group and prevent definitions other than \gdef from becoming visible outside of those blocks, so this is KaTeX's default behavior.

For example:

const macros = {
  "\\RR": "\\mathbb{R}",
};
katex.renderToString("\\let\\root=\\sqrt", {
  globalGroup: true,  // or use \global\let
  macros,
});
// macros now has a definition for "\\root"
katex.render("c = \\pm\\root{a^2 + b^2}\\in\\RR", element, {
  displayMode: true,
  macros,
});
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