js substr supports Chinese interception of function codes (Chinese is double bytes)_javascript skills

Copy code The code is as follows:

Copy code The code is as follows:

function mb_strlen(str) {
var len = 0;
for(var i = 0; i < str.length; i ) {
len = str.charCodeAt(i) < 0 || str.charCodeAt(i) > 255 ? (charset == 'utf-8' ? 3 : 2) : 1;
}
return len;
}

<form method="POST" action=""> <textarea id="testArea" name="testArea" rows="3" cols="22" onkeyup="checkFieldLength('testArea', '超过允许输入的字符个数', 20);" onchange="checkFieldLength('testArea', '超过允许输入的字符个数', 20);"> <div id="testInfo"> <span id="showMsg"> Already entered: </span> </div>