实现富文本编辑器

static/katex/README.md

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+# [<img src="https://khan.github.io/KaTeX/katex-logo.svg" width="130" alt="KaTeX">](https://khan.github.io/KaTeX/) [![Build Status](https://travis-ci.org/Khan/KaTeX.svg?branch=master)](https://travis-ci.org/Khan/KaTeX)
+
+[![Join the chat at https://gitter.im/Khan/KaTeX](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/Khan/KaTeX?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+
+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](http://www.intmath.com/cg5/katex-mathjax-comparison.php).
+ * **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. A list of supported commands can be found on the [wiki](https://github.com/Khan/KaTeX/wiki/Function-Support-in-KaTeX).
+
+## Usage
+
+You can [download KaTeX](https://github.com/khan/katex/releases) and host it on your server or include the `katex.min.js` and `katex.min.css` files on your page directly from a CDN:
+
+```html
+<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.8.3/katex.min.css" integrity="sha384-B41nY7vEWuDrE9Mr+J2nBL0Liu+nl/rBXTdpQal730oTHdlrlXHzYMOhDU60cwde" crossorigin="anonymous">
+<script src="https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.8.3/katex.min.js" integrity="sha384-L9gv4ooDLrYwW0QCM6zY3EKSSPrsuUncpx26+erN0pJX4wv1B1FzVW1SvpcJPx/8" crossorigin="anonymous"></script>
+```
+
+#### In-browser rendering
+
+Call `katex.render` with a TeX expression and a DOM element to render into:
+
+```js
+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`:
+
+```js
+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.
+- `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}`).
+
+For example:
+
+```js
+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](contrib/auto-render/README.md) 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:
+
+```css
+.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.
+
+## Contributing
+
+See [CONTRIBUTING.md](CONTRIBUTING.md)
+
+## License
+
+KaTeX is licensed under the [MIT License](http://opensource.org/licenses/MIT).