You can add properties to an object in JavaScript using dot notation or bracket notation. Here's an example using dot notation:

```javascript
const person = {
  firstName: "John",
  lastName: "Doe",
  age: 30
};

person.email = "john.doe@example.com";
person["phone"] = "555-555-5555";

console.log(person.email); 
// Output: john.doe@example.com

console.log(person.phone);
// Output: 555-555-5555
```

---

You can remove properties from an object using the `delete` keyword:

```javascript
const person = {
  firstName: "John",
  lastName: "Doe",
};

console.log(person);
// Output: { firstName: "John", lastName: "Doe" }

delete person.firstName;

console.log(person);
// Output: { lastName: "Doe" }

delete person["lastName"];

console.log(person);
// Output: {}
```

---

## Challenge Time!

Create a function called `addProperty` that takes two arguments: an object and a key. The function should add a new property to the object with a value of `null`. The function should return the object.

Then, create a function called `removeProperty` that takes two arguments: an object and a key. The function should remove the property from the object. The function should return the object.


Adding and Removing Object Properties

Challenge Time!