Is there any way to prevent replacement of JavaScript object properties?

Question

I would like to make an object\'s structure immutable, preventing its properties from being subsequently replaced. The properties need to be readable, however. Is this possi

Answer 1

Okay, so there's been already a couple of answers suggesting you return an object with several getters methods. But you can still replace those methods.

There's this, which is slightly better. You won't be able to replace the object's properties without replacing the function completely. But it's still not exactly what you want.

function Sealed(obj) {
    function copy(o){
        var n = {}; 
        for(p in o){
            n[p] = o[p]
        }
        return n;
    }
    var priv = copy(obj);
    return function(p) {
        return typeof p == 'undefined' ? copy(priv) : priv[p];  // or maybe copy(priv[p])
    }
}

var mycar = new Sealed({make:"ford", model:"mustang", color:"black"});

alert( mycar('make') ); // "ford"
alert( mycar().make );  // "ford"

var newcopy = mycar();
newcopy.make = 'volkwagen';
alert( newcopy.make ); // "volkwagen"  :(

alert( mycar().make );   // still "ford"  :)
alert( mycar('make') );   // still "ford" :)