Attention
Version 3 is now the current version of MathJax. This document is for version 2.
The MathJax Startup Sequence¶
When you load MathJax.js
into a web page, it configures itself and
immediately begins loading the components it needs. As MathJax starts
up, it uses its signaling mechanism
to indicate the actions that it is taking so that MathJax extensions
can tie into the initialization process, and so other applications
within the page can synchronize their actions with MathJax.
The startup process performs the following actions:
It creates the
MathJax
variable, and defines the following subsystems:MathJax.Object
(object-oriented programming model)MathJax.Callback
(callbacks, signals, and queues)MathJax.Ajax
(file-loading and style-creation code)MathJax.HTML
(support code for creating HTML elements)MathJax.Localization
(alternative language support)MathJax.Message
(manages the menu line in the lower left)MathJax.Hub
(the core MathJax functions)
It then creates the base
MathJax.InputJax
,MathJax.OutputJax
, andMathJax.ElementJax
objects.
MathJax sets up the default configuration, and creates the signal objects used for the startup and hub actions.
MathJax locates the
<script>
tag that loaded theMathJax.js
file, and sets theMathJax.Hub.config.root
value to reflect the location of the MathJax root directory.
MathJax determines the browser being used and its version. It sets up the
MathJax.Hub.Browser
object, which includes the browser name and version, plusisMac
,isPC
,isMSIE
, and so on.
MathJax executes the
AuthorInit()
function specified from in-lineMathJax = {...}
configuration.
MathJax sets up the
MathJax.Hub.queue
command queue, and populates it with the commands MathJax runs at startup. This includes creating theMathJax.Hub.Startup.onload
onload handler that is used to synchronize MathJax’s action with the loading of the page.
Once the MathJax.Hub.queue
is created, the following actions are
pushed into the queue:
Post the
Begin
startup signal
Perform the configuration actions:
Post the
Begin Config
startup signalLoad any configuration files specified via
config=
as a script parameterPerform author configuration from in-line
MathJax = {...}
Execute the content of the
<script>
that loaded MathJax, if it is not emptyWait for the
delayStartupUntil
condition to be met, if one was specifiedExecute any
text/x-mathjax-config
script blocksload the files listed in the
MathJax.Hub.config.config
arrayPost the
End Config
startup signal
Load the cookie values:
Post the
Begin Cookie
startup signalLoad the menu cookie values
Use the cookie to set the renderer, if it is set
Post the
End Cookie
startup signal
Define the MathJax styles:
Post the
Begin Styles
startup signalLoad the stylesheet files from the
MathJax.Hub.config.stylesheets
arrayDefine the stylesheet described in
MathJax.Hub.config.styles
Post the
End Styles
startup signal
Initialize the Message system (the grey information box in the lower left)
Load the jax configuration files:
Post the
Begin Jax
startup signalLoad the jax config files from the
MathJax.Hub.config.jax
arrayThe jax will register themselves when they are loaded
Post the
End Jax
startup signal
Load the extension files:
Post the
Begin Extensions
startup signalLoad the files from the
MathJax.Hub.config.extensions
arrayMost extensions will post a
[name] Ready
orExtension [name] Ready
startup message when they are loaded (where[name]
is the name of the extension)
Post the
End Extensions
startup signal
Set the MathJax menu’s renderer value based on the jax that have been loaded
Wait for the onload handler to fire (in MathJax v2.0 this can occur on the
DOMContentLoaded
event rather than the page’sonload
event, so processing of mathematics can start earlier)
Set
MathJax.isReady
totrue
Perform the typesetting pass (preprocessors and processors)
Post the
Begin Typeset
startup signalPost the
Begin PreProcess
hub signalRun the registered preprocessors
Post the
End PreProcess
hub signalClear the hub signal history
Post the
Begin Process
hub signalProcess the math script elements on the page
There are a number of Hub signals generated during math processing, including a signal that a
Math
action is starting (with a parameter indicating what action that is),Begin
andEnd Math Input
messages, andBegin
andEnd Math Output
signals.Each new math element generates a
New Math
hub signal with the math element’s ID
Post the
End Process
hub signalPost the
End Typeset
startup signal
Jump to the location specified in the URL’s hash reference, if any.
Initiate timers to load the zoom and menu code, if it hasn’t already been loading in the configuration (so it will be ready when the user needs it).
Post the
End
startup signal
The loading of the jax and extensions in steps 6 and 7 are now done in parallel, rather than sequentially. That is, all the jax and extensions are requested simultaneously, so they load concurrently. That means they can load in any order, and that the begin and end signals for the jax and extensions can be intermixed. (In general, you will get Begin Jax followed by Begin Extensions, but the order of End Jax and End Extensions will depend on the files being loaded.) Both 6 and 7 must complete, however, before 8 will be performed.
See the test/sample-signals.html file to see the signals in action.