trick

如何动态加载js

var newScript = document.createElement("script");
newScript.src = "https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.4/MathJax.js?config=TeX-MML-AM_CHTML";
document.getElementsByTagName('head')[0].appendChild(newScript);

同步加载
wScript);
`

同步加载