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I have a class in client side using javascript like

function ClassA(Id, value) {

    this.ID = Id;
    this.Value = value; 
    this.ListOfOtherObject = new Array();

    this.methodA = function() {
		// login here
        }

    this.methodB = function() {
		//logic here
        }
        
}

Now when I filled my object with value like

Var obj=new ClassA();
obj.ID=1;
obj.Value=’my value’;
 in the end I serialize my class obj using JSON. 
Var jsonStringOfMyObject= SerializeClassAObject(obj);

The function which I am using for serialize purpose is;

function SerializeClassAObject(aStudy) {
                    var t = typeof (aStudy);
                    if (t != "object" || aStudy === null) {
                        // simple data type   
                        if (t == "string") aStudy = '"' + aStudy + '"';
                        return String(aStudy);
                    }
                    else {
                        // recurse array or object   
                        var n, v, json = [], arr = (aStudy && aStudy.constructor == Array);
                        for (n in aStudy) {
                            v = aStudy[n]; t = typeof (v);
                            if (t == "string") v = '"' + v + '"';
                            else if (t == "object" && v !== null) v = JSON.stringify(v);
                            json.push((arr ? "" : '"' + n + '":') + String(v));
                        }
                        return (arr ? "[" : "{") + String(json) + (arr ? "]" : "}");

                        var end = "";
                        //                }
                    };
                }       

This return the JSON string which I saved on text(.txt) file. Then later when I read the txt file from my drive and de-serialize the JSON string using eval() method like;

eval("var p=" + jsonStringOfMyObject + ";");
  obj = p;

This reconstruct my ClassA obj, with all properties like ID and Value. Now if I try to call methods which are part of my ClassA then it through error “Object doesn't support this property or method”. When I did little R & D on this then I found that eval return the object with properties only and ignore all methods.
Now guys please tell how we can retain the methods of our objects?
Please note that I present simpler example, I my case my object containing other class objects which have their own methods too.
Thank you