The ECMAScript 2016 has just two small changes.
Array.prototype.includes()
Return type: boolean
Usage
let numbers = [1, 2, 3, 4];
let arr = new Array('a', 'b', 'c', 'd');
console.log(numbers.includes(2));
console.log(numbers.includes(8));
console.log(arr.includes('a'));
Output
true false true
This replaces the array.indexOf(element) which returns the index if the element is found or -1 if it isnt. This new function allows you to check for NaN (Not a Number) and this works on objects in a array too, but they must match the instance being passed.
The Exponentiation Operator (**)
Usage
let num1 = 3; let num2 = 2; console.log(3 ** 2);
Output
9
This replaces the Math.pow(3, 2) function. This new operator allows for infix notation.