katex

What is katex?

KaTeX is a fast, easy-to-use JavaScript library for TeX math rendering on the web. It provides a way to display mathematical notation in web pages, supporting a wide range of TeX functions and symbols.

What are katex's main functionalities?

Render TeX to HTML

This feature allows you to convert TeX expressions into HTML. The `renderToString` method takes a TeX string and returns an HTML string that can be inserted into a web page.

const katex = require('katex');
const html = katex.renderToString('c = \pm\sqrt{a^2 + b^2}');
console.log(html);

Render TeX to DOM

This feature allows you to render TeX expressions directly into a DOM element. The `render` method takes a TeX string and a DOM element, and it updates the element's content with the rendered math.

const katex = require('katex');
const element = document.getElementById('math');
katex.render('E = mc^2', element);

Auto-render TeX in HTML

This feature automatically finds and renders all TeX expressions within a given DOM element. The `renderMathInElement` function scans the element for TeX expressions and replaces them with rendered math.

const katex = require('katex');
const renderMathInElement = require('katex/contrib/auto-render');
renderMathInElement(document.body);

Other packages similar to katex

mathjax

MathJax is another popular JavaScript library for displaying mathematical notation in web pages. It supports a wider range of input formats, including TeX, MathML, and AsciiMath. MathJax is known for its high-quality rendering and extensive configurability, but it is generally slower than KaTeX.

asciimath

AsciiMath is a simpler alternative to KaTeX and MathJax, designed for ease of use. It uses a more human-readable syntax compared to TeX. While it is easier to write and understand, it does not support as many advanced mathematical features as KaTeX or MathJax.

README

KaTeX is a fast, easy-to-use JavaScript library for TeX math rendering on the web.

• Fast: KaTeX renders its math synchronously and doesn't need to reflow the page. See how it compares to a competitor in this speed test.
• Print quality: KaTeX’s layout is based on Donald Knuth’s TeX, the gold standard for math typesetting.
• Self contained: KaTeX has no dependencies and can easily be bundled with your website resources.
• Server side rendering: KaTeX produces the same output regardless of browser or environment, so you can pre-render expressions using Node.js and send them as plain HTML.

KaTeX supports all major browsers, including Chrome, Safari, Firefox, Opera, Edge, and IE 9 - IE 11. More information can be found on the list of supported commands and on the wiki.

Usage

You can download KaTeX and host it on your server or include the katex.min.js and katex.min.css files on your page directly from a CDN:

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.9.0-alpha2/katex.min.css" integrity="sha384-exe4Ak6B0EoJI0ogGxjJ8rn+RN3ftPnEQrGwX59KTCl5ybGzvHGKjhPKk/KC3abb" crossorigin="anonymous">
<script src="https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.9.0-alpha2/katex.min.js" integrity="sha384-OMvkZ24ANLwviZR2lVq8ujbE/bUO8IR1FdBrKLQBI14Gq5Xp/lksIccGkmKL8m+h" crossorigin="anonymous"></script>

In-browser rendering

Call katex.render with a TeX expression and a DOM element to render into:

katex.render("c = \\pm\\sqrt{a^2 + b^2}", element);

If KaTeX can't parse the expression, it throws a katex.ParseError error.

Server side rendering or rendering to a string

To generate HTML on the server or to generate an HTML string of the rendered math, you can use katex.renderToString:

var html = katex.renderToString("c = \\pm\\sqrt{a^2 + b^2}");
// '<span class="katex">...</span>'

Make sure to include the CSS and font files, but there is no need to include the JavaScript. Like render, renderToString throws if it can't parse the expression.

Rendering options

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

• displayMode: boolean. If true the math will be rendered in display mode, which will put the math in display style (so \int and \sum are large, for example), and will center the math on the page on its own line. If false the math will be rendered in inline mode. (default: false)
• throwOnError: boolean. If true, KaTeX will throw a ParseError when it encounters an unsupported command. If false, KaTeX will render the unsupported command as text in the color given by errorColor. (default: true)
• errorColor: string. A color string given in the format "#XXX" or "#XXXXXX". This option determines the color which unsupported commands are rendered in. (default: #cc0000)
• macros: object. A collection of custom macros. Each macro is a property with a name like \name (written "\\name" in JavaScript) which maps to a string that describes the expansion of the macro. Single-character keys can also be included in which case the character will be redefined as the given macro (similar to TeX active characters).
• colorIsTextColor: boolean. If true, \color will work like LaTeX's \textcolor, and take two arguments (e.g., \color{blue}{hello}), which restores the old behavior of KaTeX (pre-0.8.0). If false (the default), \color will work like LaTeX's \color, and take one argument (e.g., \color{blue}hello). In both cases, \textcolor works as in LaTeX (e.g., \textcolor{blue}{hello}).
• maxSize: number. If non-zero, all user-specified sizes, e.g. in \rule{500em}{500em}, will be capped to maxSize ems. Otherwise, users can make elements and spaces arbitrarily large (the default behavior).

For example:

katex.render("c = \\pm\\sqrt{a^2 + b^2}\\in\\RR", element, {
  displayMode: true,
  macros: {
    "\\RR": "\\mathbb{R}"
  }
});

Automatic rendering of math on a page

Math on the page can be automatically rendered using the auto-render extension. See the Auto-render README for more information.

Font size and lengths

By default, KaTeX math is rendered in a 1.21× larger font than the surrounding context, which makes super- and subscripts easier to read. You can control this using CSS, for example:

.katex { font-size: 1.1em; }

KaTeX supports all TeX units, including absolute units like cm and in. Absolute units are currently scaled relative to the default TeX font size of 10pt, so that \kern1cm produces the same results as \kern2.845275em. As a result, relative and absolute units are both uniformly scaled relative to LaTeX with a 10pt font; for example, the rectangle \rule{1cm}{1em} has the same aspect ratio in KaTeX as in LaTeX. However, because most browsers default to a larger font size, this typically means that a 1cm kern in KaTeX will appear larger than 1cm in browser units.

Libraries

Angular2+

• ng-katex Angular module to write beautiful math expressions with TeX syntax boosted by KaTeX library

Contributing

See CONTRIBUTING.md

License

KaTeX is licensed under the MIT License.

Changelog

[v0.9.0-alpha2] - 2017-11-26

Added

• Added Unicode Relations and Unicode Symbol support. Supports Unicode ∴, ∵, \mid, Arrows, Big Operators, Binary Operators, Negated Relations.
• Implemented the alignedat environment for flexible math spacing. #930
• Implemented \mathchoice command. #969
• Implemented \href command. #923
• \hspace*, \@ifstar, \@ifnextchar, \@firstoftwo (#975)
• Added \notni character ∌. #710
• Added ng-katex link to README.md. #959

Changed

• Single-character macros like active characters. #973
• Re @flow:
  • Port buildTree, katex, mathMLTree, parseTree, stretchy to @flow.

Fixed

• Fixed the spacing between columns in the {aligned} environment. #942
• Fixed issue where the {aligned} environment skips the last line if the first column is empty. #949
• Appended ApplyFunction to math functions in MathML. #960
• Changed \undertilde to \utilde. #948
• Changed frac-line from border to full span. #976