- MathJax是什么
- MathJax AsciiMath Support
- 入门指南
- MathJax Output Formats
- Loading MathJax Dynamically
- 安装和测试MathJax
- The MathJax Community
- Modifying Math on the Page
- 加载和配置MathJax
- What’s New in MathJax v2.0
- MathJax API
- Common Configurations
- What’s New in MathJax v1.1
- Describing HTML snippets
- Configuration Objects
- Migrating from MathJax v1.0 to v1.1
- CSS Style Objects
- Using MathJax in popular web platforms
- Converting to MathJax from jsMath
- Glossary
- MathJax TeX and LaTeX Support
- The MathJax Processing Model
- MathJax MathML Support
- The MathJax Startup Sequence
- Synchronizing your code with MathJax

# The MathJax Processing Model

The purpose of MathJax is to bring the ability to include mathematics

easily in web pages to as wide a range of browsers as possible.

Authors can specify mathematics in a variety of formats (e.g.,

, , or ), and MathJax provides high-quality

mathematical typesetting even in those browsers that do not have

native MathML support. This all happens without the need for special

downloads or plugins, but rendering will be enhanced if high-quality

math fonts (e.g., ) are available to the browser.

MathJax is broken into several different kinds of components: page

preprocessors, input processors, output processors, and the MathJax

Hub that organizes and connects the others. The input and output

processors are called , and are described in more detail

below.

When MathJax runs, it looks through the page for special tags that

hold mathematics; for each such tag, it locates an appropriate input

jax which it uses to convert the mathematics into an internal form

(called an element jax), and then calls an output jax to transform the

internal format into HTML content that displays the mathematics within

the page. The page author configures MathJax by indicating which

input and output jax are to be used.

Often, and especially with pages that are authored by hand, the

mathematics is not stored (initially) within the special tags needed

by MathJax, as that would require more notation than the average page

author is willing to type. Instead, it is entered in a form that is

more natural to the page author, for example, using the standard TeX

math delimiters `$...$` and `$$...$$` to indicate what part of the

document is to be typeset as mathematics. In this case, MathJax can

run a preprocessor to locate the math delimiters and replace them by

the special tags that it uses to mark the formulas. There are

preprocessors for , MathML

notation, and the that uses span and div tags.

For pages that are constructed programmatically, such as HTML

pages that result from running a processor on text in some other

format (e.g., pages produced from Markdown documents, or via programs

like tex4ht), it would be best to use MathJax’s special tags

directly, as described below, rather than having MathJax run

another preprocessor. This will speed up the final display of the

mathematics, since the extra preprocessing step would not be needed.

It also avoids the conflict between the use of the less-than sign,

`<`, in mathematics and as an HTML special character (that starts

an HTML tag), and several other issues involved in having the

mathematics directly in the text of the page (see the documentation on

the various input jax for more details on this).

## How mathematics is stored in the page

In order to identify mathematics in the page, MathJax uses special

`<script>` tags to enclose the mathematics. This is done because

such tags can be located easily, and because their content is not

further processed by the browser; for example, less-than signs can be

used as they are in mathematics, without worrying about them being

mistaken for the beginnings of HTML tags. One may also consider the

math notation as a form of “script” for the mathematics, so a

`<script>` tag makes at least some sense for storing the math.

Each `<script>` tag has a `type` attribute that identifies the

kind of script that the tag contains. The usual (and default) value

is `type="text/javascript"`, and when a script has this type, the

browser executes the script as a javascript program. MathJax,

however, uses the type math/tex to identify mathematics in the TeX

and LaTeX notation, math/mml for mathematics in MathML notation, and

math/asciimath for mathematics in AsciiMath notation. When the

tex2jax, mml2jax, or asciimath2jax preprocessors run, they

create `<script>` tags with these types so that MathJax can process

them when it runs its main typesetting pass.

For example,

<script type="math/tex">x+\sqrt{1-x^2}</script>

represents an in-line equation in TeX notation, and

<script type="math/tex; mode=display"> \sum_{n=1}^\infty {1\over n^2} = {\pi^2\over 6} </script>

is a displayed TeX equation.

Alternatively, using MathML notation, you could use

<script type="math/mml"> <math> <mi>x</mi> <mo>+</mo> <msqrt> <mn>1</mn> <mo>−<!-- − --></mo> <msup> <mi>x</mi> <mn>2</mn> </msup> </msqrt> </math> </script>

for in-line math, or

<script type="math/mml"> <math display="block"> <mrow> <munderover> <mo>∑<!-- ∑ --></mo> <mrow> <mi>n</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi mathvariant="normal">∞<!-- ∞ --></mi> </munderover> </mrow> <mrow> <mfrac> <mn>1</mn> <msup> <mi>n</mi> <mn>2</mn> </msup> </mfrac> </mrow> <mo>=</mo> <mrow> <mfrac> <msup> <mi>π<!-- π --></mi> <mn>2</mn> </msup> <mn>6</mn> </mfrac> </mrow> </math> </script>

for displayed equations in MathML notation.

As other input jax are created, they will use other types to identify

the mathematics they can process.

Page authors can use one of MathJax’s preprocessors to convert from

math delimiters that are more natural for the author to type (e.g.,

TeX math delimiters like `$$...$$`) to MathJax’s `<script>`

format. Blog and wiki software could extend from their own markup

languages to include math delimiters, which they could convert to

MathJax’s `<script>` format automatically.

Note, however, that Internet Explorer has a bug that causes it to

remove the space before a `<script>` tag if there is also a space

after it, which can cause serious spacing problems with in-line math

in Internet Explorer. There are three possible solutions to this in

MathJax. The recommended way is to use a math preview (an element

with class `MathJax_Preview`) that is non-empty and comes right

before the `<script>` tag. Its contents can be just the word

`[math]`, so it does not have to be specific to the mathematics

script that follows; it just has to be non-empty (though it could have

its style set to `display:none`). See also the `preJax` and

`postJax` options in the document for another approach.

## The components of MathJax

The main components of MathJax are its preprocessors, its input and

output jax, and the MathJax Hub, which coordinates the actions of the

other components.

**Input jax** are associated with the different script types (like

math/tex or math/mml) and the mapping of a

particular type to a particular jax is made when the various jax

register their abilities with the MathJax Hub at configuration time.

For example, the MathML input jax registers the math/mml

type, so MathJax will know to call the MathML input jax when it sees

math elements of that type. The role of the input jax is to convert

the math notation entered by the author into the internal format used

by MathJax (called an element jax). This internal format is

essentially MathML (represented as JavaScript objects), so an input

jax acts as a translator into MathML.

**Output jax** convert that internal element jax format into a

specific output format. For example, the NativeMML output jax inserts

MathML tags into the page to represent the mathematics, while the

HTML-CSS output jax uses HTML with CSS styling to lay out the

mathematics so that it can be displayed even in browsers that don’t

understand MathML. MathJax also has an output jax that

will render the mathematics using scalable vector grtaphics. Output

jax could be produced that render the mathematics using HTML5 canvas

elements, for example, or that speak an equation for blind users. The

MathJax contextual menu can be used to switch between the output jax

that are available.

Each input and output jax has a small configuration file that is

loaded when that input jax is included in the jax array in the

MathJax configuration, and a larger file that implements the core

functionality of that particular jax. The latter file is loaded the

first time the jax is needed by MathJax to process some mathematics.

Most of the combined configuration files include only the small

configuration portion for the input and output jax, making the

configuraiton file smaller and faster to load for those pages that

don’t actually incldue mathematics; the combined configurations that

end in `-full` include both parts of the jax, so there is no delay

when the math is to be rendered, but at the expense of a larger

initial download.

The **MathJax Hub** keeps track of the internal representations of the

various mathematical equations on the page, and can be queried to

obtain information about those equations. For example, one can obtain

a list of all the math elements on the page, or look up a particular

one, or find all the elements with a given input format, and so on.

In a dynamically generated web page, an equation where the source

mathematics has changed can be asked to re-render itself, or if a new

paragraph is generated that might include mathematics, MathJax can be

asked to process the equations it contains.

The Hub also manages issues concerning mouse events and other user

interaction with the equation itself. Parts of equations can be made

active so that mouse clicks cause event handlers to run, or activate

hyperlinks to other pages, and so on, making the mathematics as

dynamic as the rest of the page.

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