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
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.