## includes()

The `includes()` method is used to determine whether an array includes a certain value among its elements. It returns a boolean value indicating whether the given value is found or not.

The `includes()` method takes one required parameter, which is the value that you want to search for in the array.

```javascript
const numbers = [1, 2, 3, 4, 5];

console.log(numbers.includes(3)); // true
console.log(numbers.includes(10)); // false
```

You can also provide an optional second parameter, which is the index from which the search should start. 

```javascript
const numbers = [1, 2, 3, 4, 5];

console.log(numbers.includes(3, 4)); // false
console.log(numbers.includes(3, 1)); // true
```

In the above example, the `includes()` method returns `false` because the value `3` is not found in the array starting from index `4`, as the number `3` is on index `2`.

## indexOf()

The `indexOf()` method is used to determine the index of the first occurrence of a value in an array. It returns the index of the first occurrence of the given value, or `-1` if the value is not found.

As the `includes()` method, the `indexOf()` method takes one required parameter, which is the value that you want to search for in the array, and an optional second parameter, which is the index from which the search should start.

```javascript
const fruits = ['apple', 'banana', 'orange', 'apple', 'orange'];

console.log(fruits.indexOf('apple')); // 0
console.log(fruits.indexOf('apple', 2)); // 3
console.log(fruits.indexOf('kiwi')); // -1
```

In the above example, the `indexOf()` method returns `0` because the value `apple` is found on index `0` in the array. The second parameter is used to start the search from index `2`, so the `indexOf()` method returns `3` because the value `apple` is found on index `3` in the array.

As the value `kiwi` is not found in the array, the `indexOf()` method returns `-1`.

## lastIndexOf()

The `lastIndexOf()` method works the same way as the `indexOf()` method, but it returns the index of the last occurrence of the given value in the array. You can think of it as the `indexOf()` method, but starting the search from the end of the array.

```javascript
const fruits = ['apple', 'banana', 'orange', 'apple', 'orange'];

console.log(fruits.lastIndexOf('apple')); // 3
console.log(fruits.lastIndexOf('apple', 2)); // 0
console.log(fruits.lastIndexOf('kiwi')); // -1
```

In the above example, the `lastIndexOf()` method returns `3` because the last occurrence of the value `apple` is found on index `3` in the array. The second parameter is used to start the search from index `2`, so the `lastIndexOf()` method returns `0` because the last occurrence of the value `apple` is found on index `0` in the array if you start the search from index `2`.

As the value `kiwi` is not found in the array, the `lastIndexOf()` method returns `-1`.

## Which one to use?

The `includes()` method is the easiest to use if you just need to check if a value exists in an array.

```javascript
const fruits = ['apple', 'banana', 'orange', 'apple', 'orange'];

console.log(fruits.includes('apple')); // true
console.log(fruits.indexOf('apple') !== -1); // true
```

As you can see, the `includes()` method is much easier to read and understand than the `indexOf()` method, because it returns a boolean value while the `indexOf()` method returns a number that you need to compare with `-1`.

The `indexOf()` and `lastIndexOf()` methods are useful if you need to know the index of the first or last occurrence of a value in an array.

Ex: if you need to modify the value of the first occurrence of a value in an array, you can use the `indexOf()` method to get the index of the first occurrence of the value, and then use the index to modify the value, while the `includes()` method doesn't return the index of the value, making it useless in this case.

> Note: The `includes()`, `indexOf()` and `lastIndexOf()` also work with strings.

## Code Challenge

Create a function called `changeValue()` that takes three parameters:

1. An array of values
2. The element that you want to change
3. The new value

Ex: `changeValue(['orange', 'apple', 'banana'], 'apple', 'kiwi')` should return `['orange', 'kiwi', 'banana']`