JS Object.freeze(), Object.seal() methods

Object.freeze()

is a method that prevents modifications to an object. Once an object is frozen.

✅ You cannot add new properties.
✅ You cannot modify existing properties.
✅ You cannot delete properties.

const user = {
  name: "Alice",
  age: 25
};

Object.freeze(user);

user.age = 30;  // ❌ Won't change
user.city = "New York"; // ❌ Won't add
delete user.name; // ❌ Won't delete

console.log(user); 

// output: { name: "Alice", age: 25 }

👉 It only works on the first level. It does not freeze nested objects.

Object.seal()

is a method that prevents adding or deleting properties from an object but allows modification of existing properties.

const user = {
  name: "Alice",
  age: 25
};

Object.seal(user);

user.age = 30;  // ✅ Allowed (modification works)
user.city = "New York"; // ❌ Not allowed (new property won't be added)
delete user.name; // ❌ Not allowed (deletion won't work)

console.log(user); 

// output: { name: "Alice", age: 30 }

📌 Summary:

Feature Object.seal() | Object.freeze()
Modify properties = ✅ Yes ❌ No
Add new properties = ❌ No ❌ No
Delete properties = ❌ No ❌ No