MathML Input Processor Options

The options below control the operation of the MathML input processor that is run when you include 'input/mml' in the load array of the loader block of your MathJax configuration, or if you load a combined component that includes the MathML input jax. They are listed with their default values. To set any of these options, include an mml section in your MathJax global object.

The Configuration Block

MathJax = {
  mml: {
    parseAs: 'html',                     // or 'xml'
    forceReparse: false,                 // true to serialize and re-parse all MathML
    allowHtmlInTokenNodes: false,        // True if HTML is allowed in token nodes
    fixMisplacedChildren: true,          // True if we want to use heuristics to try to fix
                                         //   problems with the tree based on HTML not handling
                                         //   self-closing tags properly
    parseError: function (node) {        // function to process parsing errors
      this.error(this.adaptor.textContent(node).replace(/\n.*/g, ''));
    },
    verify: {                            // parameters controlling verification of MathML
      checkArity: true,                  //   check if number of children is correct
      checkAttributes: false,            //   check if attribute names are valid
      checkMathvariants: true,           //   check for valid mathvariant values
      fullErrors: false,                 //   display full error messages or just error node
      fixMmultiscripts: true,            //   fix unbalanced mmultiscripts
      fixMtables: true                   //   fix incorrect nesting in mtables
    },
    preFilters: [],                      // A list of pre-filters to add to the MathML input jax
    mmlFilters: [],                      // A list of mathml-filters to add to the MathML input jax
    postFilters: [],                     // A list of post-filters to add to the MathML input jax
  }
};

Option Descriptions

parseAs: 'html': Specifies how MathML strings should be parsed: as XML or as HTML. When set to 'xml', the browser’s XML parser is used, which is more strict about format (e.g., matching end tags) than the HTML parser, which is the default. In node applications (where the liteDOM is used), these both use the same parser, which is not very strict.

forceReparse: false: Specifies whether MathJax will serialize and re-parse MathML found in the document. This can be useful if you want to do XML parsing of the MathML from an HTML document.

allowHtmlInTokenNodes: false: HTML5 specifies that HTML can be included within token nodes in MathML. This is now supported in MathJax v4, so you can include images or form inputs, for example, in your mathematical expressions. Because this HTML is not sanitized in any way by MathJax, it is a potential security risk for sites that allow user-supplied MathML. For this reason, MathJax includes the allowHtmlInTokenNodes option, which is false by default. If you want to process HTML in MathML token nodes, set this option to true. See the HTML in MathML token nodes section for more details.

fixMisplacedChildren: true: Specifies whether MathJax should try to fix problems created by improper nesting of MathML tags. This can be due to a missing or extra close tag, or by using self-closing tags in an HTML document, where some browsers require explicit close tags for MathML.

parseError: (node) => {...}: Specifies a function to be called when there is a parsing error in the MathML (usually only happens with XML parsing). The node is a DOM node containing the error text. Your function can process that in any way it sees fit. The default is to call the MathML input processor’s error function with the text of the error (which will create an merror node with the error message). Note that this function runs with this being the MathML input processor object.

verify: {...}

This object controls what verification/modifications are to be performed on the MathML that is being processed by MathJax. The values that can be included in the verify object are the following:

checkArity: true: This specifies whether the number of children is verified or not. The default is to check for the correct number of children. If the number is wrong, the node is replaced by an <merror> node containing either a message indicating the wrong number of children, or the name of the node itself, depending on the setting of fullErrors below.

checkAttributes: false

This specifies whether the names of all attributes are checked to see if they are valid on the given node (i.e., they have a default value, or are one of the standard attributes such as style, class, id, href, or a data- attribute). If an attribute is in error, the node is either placed inside an <merror> node (so that it is marked in the output as containing an error), or is replaced by an <merror> containing a full message indicating the bad attribute, depending on the setting of fullErrors below.

Currently only names are checked, not values. Value verification may be added in a future release.

checkMathvariant: true: This specifies whether the values for the mathvariant attributes are checked for validity. If an invalid variant is used, MathJax can crash, so correct variants are important.

fullErrors: false: This specifies whether a full error message is displayed when a node produces an error, or whether just the node name is displayed (or the node itself in the case of attribute errors).

fixMmultiscripts: true: This specifies whether extra <none/> entries are added to <mmultiscripts> elements to balance the super- and subscripts, as required by the specification, or whether to generate an error instead.

fixMtables: true: This specifies whether missing <mtable>, <mtr> and <mtd> elements are placed around cells or not. When true, MathJax will attempt to correct the table structure if these elements are missing from the tree. For example, an <mtr> element that is not within an <mtable> will have an <mtable> placed around it automatically, and an <mtable> containing an <mi> as a direct child node will have an <mtr> and <mtd> inserted around the <mi>.

preFilters: []

This specifies a list of functions to run as pre-filters for the MathML input jax. Each entry is either a function, or an array consisting of a function followed by a number, which is the priority of the pre-filter (lower priorities run first). The functions are passed an object with three properties: math, giving the MathItem being processed, document giving the MathDocument for the math item, and data giving the serialized MathML string to be parsed. The pre-filters are executed only when the MathML input jax is asked to process a mathml string (such as when MathJax.mathml2svg() is called), or when the forceReparse option is set. When the MathML is taken directly from a document DOM, it is already parsed, and so is not a serialized MathML string.

See the MathJax Pre- and Post-Filters section for examples of pre-filters.

mmlFilters: []: This specifies a list of functions to run as MathML-filters for the MathML input jax. Each entry is either a function, or an array consisting of a function followed by a number, which is the priority of the pre-filter (lower priorities run first). The functions are passed an object with three properties: math, giving the MathItem being processed, document giving the MathDocument for the math item, and data giving the MathML DOM elements for the expression. The MathML-filters are executed just before the MathML input jax converts the DOM elements into MathJax’s internal format. This can be used to manipulate the expression before it is processed.

postFilters: []

This specifies a list of functions to run as post-filters for the MathML input jax. Each entry is either a function, or an array consisting of a function followed by a number, which is the priority of the pre-filter (lower priorities run first). The functions are passed an object with three properties: math, giving the MathItem being processed, document giving the MathDocument for the math item, and data giving the root of the internal representation of the MathML tree (the internal form of the top-level <math> node). The post-filters are executed when the MathML input jax has finished converting it to the internal MathML format, but before the MathItem’s root property is set.

See the MathJax Pre- and Post-Filters section for examples of post-filters.

Developer Options

In addition to the options listed above, low-level options intended for developers include the following:

FindMathML: null: The FindMathML object instance that will override the default one. This allows you to create a subclass of the FindMathML class, create an instance of it, and pass that to the MathML input jax to use in place of the default one. A null value means use the usual FindMathML class and make a new instance of that.

MathMLCompile: null: The MathMLCompile object instance that will override the default one. This allows you to create a subclass of the MathMLCompile class, make an instance of it, and pass that to the MathML input jax to use in place of the default one. A null value means use the usual MathMLCompile class and make a new instance of that.

MmlFactory: null: The MmlFactory object instance the will override the default one. This allows you to create a subclass of the MmlFactory class, make an instance of it, and pass that to the MathML input jax to use in place of the default one. A null value means use the usual MmlFactory class and make a new instance of that.