Is it possible to access an object within itself?

Question

Cadastro = {
    "descricao" : "Novo usuário",
    "editando" : false
}

It is possible at runtime I get the value of the property by "editing" and use it?

Something like:

Cadastro = {
    "descricao" : "Novo usuário",
    "editando" : false,
    "titulo" : "editando" ? "Editar" : "Criar"
}

I found a way but it is not using the property but creating a variable in the global scope:

window.editando = true;
Cadastro = {
    "descricao" : "Novo usuário",
    "editando" : false,
    "titulo" : (window.editando ? "Editar" : "Novo")
}

Is there any other way to do this? What I want is when the variable value changes the return value "title" also changes.

Answer 1

code, you can do as follows:

var Cadastro = function (descricao, editando) {
  this.descricao = descricao;
  this.editando = editando;
};

Object.defineProperty(Cadastro.prototype, "titulo", {
  get: function () { return this.editando ? "Editar" : "Criar"; },
  enumerable: true
});

var cadastro1 = new Cadastro("Novo usuário", false);
console.log(cadastro1.titulo); // Criar

var cadastro2 = new Cadastro();
cadastro2.descricao = "Novo perfil";
cadastro2.editando = true;
console.log(cadastro2.titulo); // Editar

Due to your implementation, you may encounter some difficulty because of the combination of Object.defineProperty and *.prototype, in this case define the property in the constructor of the "Class".

var Cadastro = function (descricao, editando) {
  this.descricao = descricao;
  this.editando = editando;

  Object.defineProperty(this, "titulo", this.descriptor.titulo);
};

Cadastro.prototype.descriptor = {};
Cadastro.prototype.descriptor.titulo = {
  get: function () { return this.editando ? "Editar" : "Criar"; },
  enumerable: true
}

var cadastro1 = new Cadastro("Novo Usuario", true);
var cadastro2 = new Cadastro("Novo Perfil", false);

console.log(JSON.stringify(cadastro1));
console.log(JSON.stringify(cadastro2));

Answer 2

var Cadastro = {
    descricao: "Novo usuário",
    editando: false,
    get titulo() {
        if (this.editando) {
            return "Editar";
        } else {
            return "Criar";
        }
    }
};

console.log(Cadastro.titulo);
Cadastro.editando = true;
console.log(Cadastro.titulo);

Answer 3

With that with a little gambiarra it is possible yes.

Use a self-invoking Function making and use the this, so you will reference the object itself. I used the property __init to be able to refer to the object itself. Hence, as the variable this is only not accessible in the context of declaration, I call it at the end of the object declaration. So that variable Cadastro import the declaration value of our object, it is necessary to return the this at the end of that function.

See this as a "constructor" of our object.

Cadastro = {
    "descricao" : "Novo usuário",
    "editando" : false,
    "__init" : function ()
    {
          alert(this.editando)

          this.titulo = this.editando ? "Editar" : "Novo";
          return this;
    }
}.__init()

Check out on Jsfiddle

In that case, it is necessary that the this is within the context of the object you want to reference (in this case our anonymous function references Cadastro). If you use the this outside an object context, the reference will be window.

Another way to make that statement you need would be to declare that index titulo after declaring the object. Do so:

Cadastro = {
    "descricao" : "Novo usuário",
    "editando" : false,
}

Cadastro.titulo = Cadastro.editando ? "Editar" : "Novo";

Answer 4

The simplest and practical way:

Cadastro = {
    descricao: "Novo usuário",
    editando: false,
    titulo: function () {
        return this.editando ? "Editar" : "Novo";
    }
}

// Depois é so chamar quando precisar
console.log(Cadastro.titulo());
Cadastro.editando = true;
console.log(Cadastro.titulo());