//generator是可以用来控制迭代器的函数，可以暂停，也可以任何时候恢复
function * loop () {
   for(let i = 0; i < 5; i++) {
      yield console.log(i)
   }
}

const l = loop()
l.next()
l.next()

function * gen () {
  let val
  val = (yield [1,2,3]) + 7
  console.log(val)
}

const l = gen()
console.log(l.next(10))
l.return(100)
l.next(20)

//捕获错误
function * gen () {
  while (true) {
     try {
       yield 1
     }catch (e) {
       console.log(e.message)
     }
  }
}
const g = gen()
console.log(g.next())
console.log(g.next())
console.log(g.next())
g.throw(new Error('ss'))
console.log(g.next())