ES5 Defining Unchangeable Arrays / Property Values

Question

When defining an array as a property of an ES5-style object, I want to make it so the property's value cannot be changed.

'use strict';

var global = Object.create(Object.prototype, {
    names: {
        value: ['Barney', 'Trogdor'],
        writable: false
    }
});

global.names.push('Jackson'); // I expected a read-only error here

console.log(global.names[2]); // >> Jackson

global.names = ['Ooga', 'Booga']; // >> TypeError: "names" is read-only

It seems that I have only protected against property assignment.

Is there any way to protect against stuff like Array.push() that modifies my "unwritable" array?

Answer 1

Once all the data is loaded, why not overwrite the push method on what you have:

global.names.push = function () {return false}

Answer 2

Object.seal() seems to work.

'use strict';

var global = Object.create(Object.prototype, {
    names: { value: Object.seal(['Barney', 'Trogdor']) }
});
global.names.push('Jackson'); // >> TypeError: global.names.push(...) is not extensible

---

EDIT: Actually, nevermind.

In the previous example, were I to append the following line of code:

global.names[0] = 'Jackson'; // Still works

I believe Object.freeze() was what I actually wanted.

var global = Object.create(Object.prototype, {
    names: { value: Object.freeze(['Barney', 'Trogdor']) }
});
global.names.push('Jackson');  // >> TypeError: global.names.push(...) is not extensible
global.names[0] = 'Jackson';   // >> TypeError: 0 is read-only
global.names = ['Jackson'];    // >> TypeError: "names" is read-only