一. includes

ES7: includes ES5: indexOf

1. 判断

const arr = ['西游记', '红楼梦', '三国演义', '水浒传']
console.log(arr.includes('西游记'))      // true
console.log(arr.includes('太乙真人'))     // false

2. **
console.log(2 ** 10)              // 1024
console.log(Math.pow(2, 10))      // 1024