The MathJax Startup SequenceΒΆ

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, and MathJax.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 the MathJax.js file, and sets the MathJax.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, plus isMac, 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 the MathJax.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:

  1. Post the Begin startup signal
  1. Perform the configuration actions:
    • Post the Begin Config startup signal
    • Execute the content of the <script> that loaded MathJax, or load the config/MathJax.js file if the <script> is empty
    • If the MathJax.Hub.config.delayStartupUntil value is set, wait until its condition is met
    • load the files listed in the MathJax.Hub.config.config array
    • Post the End Config startup signal
  1. 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
  1. 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
  1. 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
  1. 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)
    • Post the End Extension startup signal
  1. Wait for the onload handler to fire
  1. Set MathJax.isReady to true
  1. 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
    • Post the End Process hub signal
    • Post the End Typeset startup signal
  1. Post the End startup signal