<!DOCTYPE html><html><head><meta charset="UTF-8"><title>Document</title><script type="text/javascript">var a = 1;var b = 2;function *foo() {a++;yield;b = b * a;a = (yield b) + 3;}function *bar() {b--;yield;a = (yield 8) + b;b = a * (yield 2);}function step(gen) {var it = gen();var last;return function() {last = it.next( last ).value;console.log( a, b, last );};}var s1 = step( foo );var s2 = step( bar );s2();s2();s1();s2();s1();s1();s2();console.log( a, b );</script></head><body></body></html>
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fdsgasgg
TA贡献19条经验 获得超12个赞
代码执行到 yield 时候才会交出执行权.
你认为是24是因为你认为bar最后一次执行时候a应该是12，其实a在s2执行yield 2时候已经赋值为9了,因为计算是从左到右执行的，
你可以结合下面的代码感受下
function* gen1(){
console.log('g1', a * (yield 2))
}
function* gen2(){
console.log('g2', (yield 2) * a)
}
var g1 = gen1(), g2 = gen2(), a = 9
g1.next()
g2.next()
a = 12
g1.next(2) // 18
g2.next(2) // 24
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