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# The MathJax.InputJax Class

Input jax are the components of MathJax that translate mathematics from its original format (like TeX or MathML) to the MathJax internal format (an element jax).

An input jax is stored as a pair of files in a subdirectory of the `jax/input` directory, with the subdirectory name being the name of the input jax. For example, the TeX input jax is stored in jax/input/TeX. The first file, `config.js`, is loaded when MathJax is being loaded and configured, and is indicated by listing the input jax directory in the jax array of the MathJax configuration. The `config.js` file creates a subclass of the MathJax.InputJax object for the new input jax and registers that with MathJax, along with the MIME-type that will be used to indicate the mathematics that is to be processed by the input jax.

The main body of the input jax is stored in the second file, `jax.js`, which is loaded when the input jax is first called on to translate some mathematics. This file augments the original input jax subclass with the additional methods needed to do the translation. MathJax calls the input jax’s `Translate()` method when it needs the input jax to translate the contents of a math `<script>` tag.

The MathJax.InputJax class is a subclass of the MathJax Jax class, and inherits the properties and methods of that class. Those listed below are the additional or overridden ones from that class.

## Properties

`id`

  The name of the jax.

`version`

  The version number of the jax.

`directory`

  The directory where the jax files are stored (e.g., `"[MathJax]/jax/input/TeX"`).

`elementJax`

  The name of the ElementJax class that this input jax will produce (typically `mml`, as that is the only ElementJax at the moment).

## Methods

`Process`(script, state)

  This is the method that the `MathJax.Hub` calls when it needs the input jax to process the given math `<script>`. Its default action is to do the following:

  1. Start loading any element jax specified in the `elementJax` array;
  2. Start loading the jax’s `jax.js` file;
  3. Start loading the required output jax (so it is ready when needed); and
  4. Redefine itself to simply return the callback for the load operation (so that further calls to it will cause the processing to wait for the callback).

  Once the `jax.js` file has loaded, this method is replaced by the jax’s `Translate()` method (see below), so that subsequent calls to `Process()` will perform the appropriate translation.

  Parameters : | script — reference to the DOM `<script>` object for the mathematics to be translated state — a structure containing information about the current proccessing state of the mathematics (internal use)
  Returns : | an ElementJax object, or `null`

`Translate`(script, state)

  This is the main routine called by MathJax when a `<script>` of the appropriate type is found. The default `Translate()` method throws an error indicating that `Translate()` hasn’t been defined, so when the `jax.js` file loads, it should override the default `Translate()` with its own version that does the actual translation.

  The translation process should include the creation of an Element Jax that stores the data needed for this element.

  Parameters : | script — the `<script>` element to be translated state — a structure containing information about the current proccessing state of the mathematics (internal use)
  Returns : | the element jax resulting from the translation

`Register`(mimetype)

  This registers the MIME-type associated with this input jax so that MathJax knows to call this input jax when it sees a `<script>` of that type. An input jax can register more than one type, but it will be responsible for distinguishing elements of the various types from one another.

  Parameters : | mimetype — the MIME-type of the input this jax processes
  Returns : | `null`

`needsUpdate`(jax)

  This implements the element jax’s `needsUpdate()` method, and returns `true` if the `jax` needs to be rerendered (i.e., the text has changed), and `false` otherwise.

  Perameters : | jax — the element jax to be checked
  Returns : | `true` if the jax’s text has changed, `false` otherwise

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