JS判断字符串长度（英文占1个字符，中文汉字占2个字符）

String.prototype.gblen = function() {  
    var len = 0;  
    for (var i=0; i<this.length; i++) {  
        if (this.charCodeAt(i)>127 || this.charCodeAt(i)==94) {  
             len += 2;  
         } else {  
             len ++;  
         }  
     }  
    return len;  
}

function strlen(str){
    var len = 0;
    for (var i=0; i<str.length; i++) { 
     var c = str.charCodeAt(i); 
    //单字节加1 
     if ((c >= 0x0001 && c <= 0x007e) || (0xff60<=c && c<=0xff9f)) { 
       len++; 
     } 
     else { 
      len+=2; 
     } 
    } 
    return len;
}

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;
}

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

// 把双字节的替换成两个单字节的然后再获得长度
getBLen = function(str) {
    if (str == null) return 0;
    if (typeof str != "string"){
        str += "";
    }
    return str.replace(/[^\x00-\xff]/g,"01").length;
}