//計算字符串，字符長度
         getByteLen: function(vale) {
             var val = vale ? vale : "";
            var len = 0;
            for (var i = 0; i < val.length; i++) {
                 var a = val.charAt(i);
                 if (a.match(/[^\x00-\xff]/ig) != null) 
                {
                    len += 2;
                }
                else
                {
                    len += 1;
                }
            }
            return len;
        }

      //調(diào)用方法    
      modelName = "張三李四王五"
      if (XXXX.getByteLen(modelName) > 30 ) {
            alert("不能超過30長度")
      }