Question: Beyond the improved readability, is there any advantage to `includes` over `indexOf`? They seem identical to me.

What is the difference between this

```
var x = [1,2,3].indexOf(1) > -1; //true

```

And this? 

```
var y = [1,2,3].includes(1); //true

```

Answer: 
Conceptually you should use indexOf when you want to use the position indexOf just give you to extract the value or operate over the array, i.e using slice, shift or split after you got the position of the element. On the other hand, Use Array.includes only to know if the value is inside the array and not the position because you don't care about it.
`indexOf()` and `includes()` can both be used to find elements in an array, however each function yields different return values.

`indexOf` returns a number (`-1` if element not present in the array, or array position if the element is present).

`includes()` returns a boolean value (`true` or `false`).