Javascript restricts the user to typing Chinese characters

This article is an example of how javascript can restrict users to typing Chinese characters. Share with you for your reference. The specific implementation method is as follows:

To verify the function, we must understand that if it is a Chinese character, then the string length plus 2, if the regular we directly use \\u4E00-\\u9FA5 can solve.

1. Unicode tests Chinese characters

function chkstrlen(str) 

{ 

　　　　var strlen = 0; 

　　　　for(var i = 0;i < str.length; i++) 

　　　　{ 

　　　　　　if(str.charCodeAt(i) > 255) //If it is a Chinese character, then the string length plus 2 

　　　　　　　　strlen += 2; 

　　　　　　else

　　　　　　　　strlen++; 

　　　　} 

　　　　return   strlen; 

}