获取中文转化为英文后字符串长度

getLength = function(str) {
    // 先把中文替换成两个字节的英文，再计算长度
    return str.replace(/[\u0391-\uFFE5]/g,"aa").length;
}

var length = str.length;
var blen = 0;
for (i=0; i<length; i++) {
  // Unicode编码,Unicode的前128个字符编码和ASCII是一致的，即向后兼容ASCII
  if ((str.charCodeAt(i) & 0xff00) != 0) {
    blen ++;
  }
  blen ++;
}

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;
    }
    return realLength;
};