1. 首先看一下JS实现方法，此方法在网上找的，具体地址忘了，代码如下：
String.prototype.format= function () {
        if (arguments.length == 0) return this;
        var param = arguments[0];
        var s = this;
        if (typeof (param) == 'object') {
            for (var key in param)
                s = s.replace(new RegExp("\\{" + key + "\\}", "g"), param[key]);
            return s;
        } else {
            for (var i = 0; i < arguments.length; i++)
                s = s.replace(new RegExp("\\{" + i + "\\}", "g"), arguments[i]);
            return s;
        }
    }

javascript调用：

var str = "js实现用{two}自符串替换占位符{two} {three}  {one} ".format({one: "I",two: "LOVE",three: "YOU"});
var str2 = "js实现用{1}自符串替换占位符{1} {2}  {0} ".format("I","LOVE","YOU");

2.C#后台实现代码，下面方法自己写的；

        /// 
        /// 字符串格式占位替换
        /// 
        /// 字符串
        /// 替换对象（T,匿名对象，Newtonsoft.Json.Linq.JObject）
        /// 
        public static string Format(string str, object obj)
        {
            if (str.Length == 0)
            {
                return str;
            }
            string s = str;
            if (obj.GetType().Name == "JObject")
            {
                foreach (var item in (Newtonsoft.Json.Linq.JObject)obj)
                {
                    var k = item.Key.ToString();
                    var v = item.Value.ToString();
                    s = Regex.Replace(s, "\\{" + k + "\\}", v, RegexOptions.IgnoreCase);
                }
            }
            else
            {
                foreach (System.Reflection.PropertyInfo p in obj.GetType().GetProperties())
                {
                    var xx = p.Name;
                    var yy = p.GetValue(obj).ToString();
                    s = Regex.Replace(s, "\\{" + xx + "\\}", yy, RegexOptions.IgnoreCase);
                }
            }
            return s;
        }

c#调用方法：

 string ssew = "{one:'I',two: 'LOVE',three: 'YOU'}";
            Newtonsoft.Json.Linq.JObject o2 = Newtonsoft.Json.Linq.JObject.Parse(ssew);
            string sew = CommonFunc.Format("{ONE} {TWO} {three}  ", o2);

            var ste = new { one = "I", two = "LOVE", three = "You" };
            string ese = CommonFunc.Format("{ONE} {TWO} {three}  ", ste);