test/sample-dynamic-steps.html

<!DOCTYPE html>
<html>
<head>
<title>MathJax Dynamic Steps Test Page</title>
<!-- Copyright (c) 2011-2015 The MathJax Consortium -->
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1">

<script type="text/x-mathjax-config">
  //
  //  Make displayed equations be aligned left and indented
  //
  MathJax.Hub.Config({
    displayAlign: "left",
    displayIndent: "2em"
  });
  //
  //  Enable the step button after the equation is typeset
  //
  MathJax.Hub.Queue(function () {
    document.getElementById("step").disabled = false;
  });
</script>
<script type="text/javascript" src="../MathJax.js?config=TeX-AMS_HTML-full"></script>

<script type="text/javascript">
//
//  Use a closure to hide the local variable
//
(function () {
  var n = 1;

  //
  //  Make the current step be visible, and increment the step.
  //  If it is the last step, disable the step button.
  //  Once a step is taken, the reset button is made available.
  //
  window.ShowStep = function () {
    document.getElementById("Step"+n).style.visibility = "visible"; n++;
    if (!document.getElementById("Step"+n)) {document.getElementById("step").disabled = true}
    document.getElementById("reset").disabled = false;
  }

  //
  //  Enable the step button and disable the reset button.
  //  Hide the steps.
  //
  window.ResetSteps = function () {
    document.getElementById("step").disabled = false;
    document.getElementById("reset").disabled = true;
    var i = 1, step; n = 1;
    while (step = document.getElementById("Step"+i)) {step.style.visibility = "hidden"; i++}
  }
})();
</script>

<style>
/*
 *  Start with the steps being hidden
 */
#Step1, #Step2, #Step3, #Step4, #Step5 {
  visibility: hidden;
}

h1 {
  background: #CCCCCC;
  padding: .2em 1em;
  border-top: 3px solid #666666;
  border-bottom: 3px solid #999999;
}
</style>

</head>
<body>

<h1>Dynamic Equations in MathJax</h1>

<blockquote>
<p>
Expand the following:
\begin{align}
  (x+1)^2
    &\cssId{Step1}{= (x+1)(x+1)}\\
    &\cssId{Step2}{= x(x+1) + 1(x+1)}\\
    &\cssId{Step3}{= (x^2+x) + (x+1)}\\
    &\cssId{Step4}{= x^2 + (x + x) + 1}\\
    &\cssId{Step5}{= x^2+2x+1}\\
\end{align}
</p>

<input type="button" onclick="ShowStep()" value="Show Next Step" id="step" disabled="true" />
<input type="button" onclick="ResetSteps()" value="Reset" id="reset" disabled="true" />
</blockquote>

</body>
</html>