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

You can now force a single object property to be frozen instead of freezing the whole object. You can achieve this with Object.defineProperty and the parameter writable: false

var obj = {
    "first": 1,
    "second": 2,
    "third": 3
};
Object.defineProperty(obj, "first", {
    writable: false,
    value: 99
});

In this example, obj.first now has its value locked to 99.