JavaScript appears garbled in alert ()

When writing jquery code today, alert () always appears garbled in Chinese

Pondering for a while, the information on the Internet is the HTML page set charset to GB2312

<charset= "GB2312"/><http-equiv = "Content-type" content = "text/html; charset=gb2312" />

Turns out it's still garbled.

Finally found that the reference I wrote the JS file set CharSet to GB2312, and then there is no garbled

<charset= "GB2312"  src= ". /.. /resource/js/informix.login.js "></script>

JavaScript appears garbled in alert ()