<script type="text/javascript">
        var App = {
            chars : "!\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~",
            rplstr : "~!@#$%^&*", //要过滤的字符
            encode : function(str){
                var self = this;
                var reg = new RegExp("\\" + this.rplstr.split('').join('|\\'), "g");
                str = str.replace(reg, function(v){return "{"+ (self.chars.indexOf(v) + 32) + "}";});
                return str;
            },
            decode : function(str){
                var self = this;
                str = str.replace(/{\d+}/g, function(v){return self.chars.charAt(parseInt(v.replace(/{|}/g, ""), 10)-32);});
                return str;
            }
        }
        var str = "你好@{123*&%ABC"
        str = App.encode(str);
        alert(str);
        str = App.decode(str);
        alert(str);
        
    </script>

------解决方案--------------------
JScript code

  var p = /(@|%40)/;
var t = "你好@";
t = t.replace(p,"-");
alert(t);
var p0 = /(-|%2D)/;
t = t.replace(p0,"@");
alert(t);