How to make the source(path) of MathJax.js environment dependent?
<script src="https://c328740.ssl.cf1.rackcdn.com/mathjax/latest/MathJax.js"></script>
<script>
if( !window.MathJax ) {
    document.write(
        '<script type="text/javascript" src="../lib/MathJax.js"></script>'
    );
}
</script>

<script>
var url= location.protocol == 'http:'?
         "https://c328740.ssl.cf1.rackcdn.com/mathjax/latest/MathJax.js" :
         "../lib/MathJax.js";
document.write(
    '<script type="text/javascript" src="' + url + '"></script>'
);
</script>