Attention
Version 3 is now the current version of MathJax. This document is for version 1.
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.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 set 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 signal - Load any configuration files specified via
config=
as a script parameter - Execute the content of the
<script>
that loaded MathJax, if it is not empty - Wait for the
delayStartupUntil
condition to be met, if one was specified - Execute any
text/x-mathjax-config
script blocks - load the files listed in the
MathJax.Hub.config.config
array - Post the
End Config
startup signal
- Post the
- Load the cookie values:
- Post the
Begin Cookie
startup signal - Load the menu cookie values
- Use the cookie to set the renderer, if it is set
- Post the
End Cookie
startup signal
- Post the
- Define the MathJax styles:
- Post the
Begin Styles
startup signal - Load the stylesheet files from the
MathJax.Hub.config.stylesheets
array - Define the stylesheet described in
MathJax.Hub.config.styles
- Post the
End Styles
startup signal
- Post the
- Load the jax configuration files:
- Post the
Begin Jax
startup signal - Load the jax config files from the
MathJax.Hub.config.jax
array- The jax will register themselves when they are loaded
- Post the
End Jax
startup signal
- Post the
- Load the extension files:
- Post the
Begin Extension
startup signal - Load the files from the
MathJax.Hub.config.extensions
array- Most extensions will post a
Extension [name] Ready
startup message when they are loaded (where[name]
is the name of the extension)
- Most extensions will post a
- Post the
End Extension
startup signal
- Post the
- Set the MathJax menu’s renderer value based on the jax that have been loaded
- Wait for the onload handler to fire
- Set
MathJax.isReady
totrue
- Perform the typesetting pass (preprocessors and processors)
- Post the
Begin Typeset
startup signal - Post the
Begin PreProcess
hub signal - Run the registered preprocessors
- Post the
End PreProcess
hub signal - Clear the hub signal history
- Post the
Begin Process
hub signal - Process the math script elements on the page
- Each new math element generates a
New Math
hub signal with the math element’s ID
- Each new math element generates a
- Post the
End Process
hub signal - Post the
End Typeset
startup signal
- Post the
- Post the
End
startup signal
The loading of the jax and extensions in steps 5 and 6 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 5 and 6 must complete, however, before 7 will be performed.
See the test/sample-signals.html
file to see the signals in action.