使用javascript修改Mathjax的变量颜色

<script src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.7/MathJax.js?config=TeX-MML-AM_CHTML"></script>

<script type="text/x-mathjax-config">
  MathJax.Hub.Config({
    tex2jax: {
      inlineMath: [['$', '$'], ['\\(', '\\)']],
      processEscapes: true
    }
  });
</script>

<script type="text/javascript">
  window.addEventListener("load", function() {
    var math = document.getElementsByClassName("math");
    for (var i = 0; i < math.length; i++) {
      var variables = math[i].getElementsByClassName("mi");
      for (var j = 0; j < variables.length; j++) {
        variables[j].style.color = "red";
      }
    }
  });
</script>