var jmz = {};
jmz.GetLength = function(str) {
  ///<summary>获得字符串实际长度，中文2，英文1</summary>
  ///<param name="str">要获得长度的字符串</param>
  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;
  }
  return realLength;
};

alert(jmz.GetLength('测试测试ceshiceshi));

var l = str.length;
var blen = 0;
for(i=0; i<l; i++) {
if ((str.charCodeAt(i) & 0xff00) != 0) {
blen ++;
}
blen ++;
}

var jmz = {};
jmz.GetLength = function(str) {
  return str.replace(/[\u0391-\uFFE5]/g,"aa").length;  //先把中文替换成两个字节的英文，在计算长度
};  
alert(jmz.GetLength('测试测试ceshiceshi'));