javascript - ES6 中的生成器

Question

我创建了一个使用 es6 生成器生成斐波那契数列的函数:

//WARNING CAUSES INFINITE LOOP
function* fibonacci(limit = Infinity) {
  let current = 0
  let next = 1

  while (current < limit) {
    yield current
      [current, next] = [next, current + next]
  }
}

for (let n of fibonacci(200)) {
  console.log(n)
}

上面的函数不会交换两个数字，而如果在任何其他函数中正常完成，则会交换两个数字。运行这个函数时我得到一个无限循环。为什么变量交换不起作用？

Answer 1

您遇到语法错误:缺少分号会使引擎将您的语句解析为

yield (current [ current, next ] = [ next, current + next ])
//             ^        ^
// property access    comma operator

如果你想省略分号和 let them be automatically inserted只要可能需要，您将 need to put one at the begin以 (, [, /, +, - 开头的每一行或`:

function* fibonacci(limit = Infinity) {
  let current = 0
  let next = 1

  while (current < limit) {
    yield current
    ;[current, next] = [next, current + next]
  }
}

for (let n of fibonacci(200)) {
  console.log(n)
}