javascript – for..of和迭代器状态

考虑一下这个 python代码

it = iter([1,2,3,4,5])

for x in it:
    print x
    if x == 3:
        break

print '---'

for x in it:
    print x

它打印1 2 3 — 4 5,因为迭代器会记住它在循环中的状态.当我在JS中看似相同的事情时,我得到的只是1 2 3 —.

function* iter(a) {
    yield* a;
}

it = iter([1,5])

for (let x of it) {
    console.log(x)
    if (x === 3)
        break
}

console.log('---')

for (let x of it) {
    console.log(x)
}

我错过了什么？

解决方法

不幸的是,JS中的Generator对象不可重用.
在 MDN清楚地说明

Generators should not be re-used,even if the for…of loop is terminated early,for example via the break keyword. Upon exiting a loop,the generator is closed and trying to iterate over it again does not yield any further results.