# The ES2016 Guide

> Discover the two features added in ES2016 (ES7): Array.prototype.includes for cleanly checking if an array contains a value, and the exponentiation operator.

Author: [Flavio Copes](https://flaviocopes.com/about/) | Published: 2018-10-01 | Topics: [JavaScript](https://flaviocopes.com/tags/js/) | Canonical: https://flaviocopes.com/es2016/

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- [Array.prototype.includes()](#arrayprototypeincludes)
- [Exponentiation Operator](#exponentiation-operator)

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ES2016, officially known as ECMAScript 2016, was finalized in June 2016.

Compared to ES2015, ES2016 is a tiny release for [JavaScript](https://flaviocopes.com/javascript/), containing just two features:

- Array.prototype.includes
- Exponentiation Operator

## Array.prototype.includes()

This feature introduces a more readable syntax for checking if an array contains an element.

With ES6 and lower, to check if an array contained an element you had to use `indexOf`, which checks the index in the array, and returns `-1` if the element is not there.

Since `-1` is evaluated as a true value, you could **not** do for example

```js
if (![1,2].indexOf(3)) {
  console.log('Not found')
}
```

With this feature introduced in ES2016 we can do

```js
if (![1,2].includes(3)) {
  console.log('Not found')
}
```

## Exponentiation Operator

The exponentiation operator `**` is the equivalent of `Math.pow()`, but brought into the language instead of being a library function.

```js
Math.pow(4, 2) == 4 ** 2
```

This feature is a nice addition for math intensive JS applications.

The `**` operator is standardized across many languages including [Python](https://flaviocopes.com/python-introduction/), Ruby, MATLAB, Lua, Perl and many others.