Srisa Srisa - 12 days ago 6
Javascript Question

How to prevent object properties to not be extended in javascript

Im trying to seal an object property .

My question is ,here i have given Object.seal(personObject),this particular object is sealed and does not allow to configure or make any extensions in this object,but as i did not mention on personObject_2 it does allow to extend or configure

How can i make it on prototype .I mean like any class of type person should have/respect this seal.Can we achieve such behaviour



"use strict";
var personModule=(function (module) {
var person=function (fname,lname) {
Object.defineProperty(this,'firstName',{
get:function () {
return fname;
}
,set:function (newValue) {
fname=newValue;
},
configurable:true
});

Object.defineProperty(this,'lastName',{
get:function () {
return lname;
}
,set:function (newValue) {
lname=newValue;
},
configurable:true
});

Object.defineProperty(this,'fullName',{
get:function () {
return fname+lname;
},
configurable:true
});

}
module.person=person;
return module;
})(personModule || {});

var personObject=new personModule.person( "Raju","Rani");
console.log(personObject.fullName);
Object.seal(personObject);
//delete personObject.firstName;-->It throws error here




var personObject2=new personModule.person( "Shiva","Kumar");

delete personObject2.firstName;

console.log(personObject2.firstName);





Thanks

Answer

Here is Proxy version in case you do not prefer adding Object.seal on constructor

"use strict";
var personModule=(function (module) {
   var  person=function (fname,lname) {
   Object.defineProperty(this,'firstName',{
      get:function () {
        return fname;
      }
      ,set:function (newValue) {
        fname=newValue;
     },
     configurable:true
   });

   Object.defineProperty(this,'lastName',{
     get:function () {
       return lname;
     }
     ,set:function (newValue) {
       lname=newValue;
     },
     configurable:true
   });

   Object.defineProperty(this,'fullName',{
     get:function () {
       return fname+lname;
     },
     configurable:true
   });

 }
 module.person=new Proxy(person, {
     construct(target, args){
         args.unshift(null);
         let ctor = target.bind.apply(target, args);
         let result = new ctor();
         Object.seal(result);
         return result;
     }
 });
 return module;
})(personModule || {});

var personObject=new personModule.person( "Raju","Rani");
console.log(personObject.fullName);
Object.seal(personObject);
//delete personObject.firstName;-->It throws error here




var personObject2=new personModule.person( "Shiva","Kumar");

delete personObject2.firstName;

console.log(personObject2.firstName);