1. ES2016新特性.md

ES2016(ES7)新特性

参考：The final feature set of ECMAScript 2016 (ES7)

1. Array.prototype.includes(value : any) : boolean

Examples:

['a', 'b', 'c'].includes('a');
// true
['a', 'b', 'c'].includes('d');
// false

2. exponentiation operator (**)，求幂运算符

类似：

Math.pow(3, 2); // 9

Examples:

let squared = 3 ** 2; // 9

let num = 3;
num **= 2;
console.log(num); // 9