js判断字符长度及中英文数字等

<script type="text/javascript"> 
var zfl={}; 
zfl.GetLength = function(str){ 
var realLength = 0,len = str.length,charCode = -1; 
for(var i=0;i<len;i++){ 
charCode = str.charCodeAt(i); 
if(charCode>0 && charCode<=128) realLength +=1; 
else realLength += 2; 
else realLength += 2; 
else realLength += 2; 
<script type="text/javascript"> 
alert(zfl.GetLength("中国123zkrljl")); 
</script>