实现每隔i秒循环打印i

面试时候的一道题，实现如下功能：

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输出 1 
间隔 1s 
输出 2 
间隔 2s 
输出 3 
间隔 3s 
输出 1 
间隔 1s 
输出 2 
间隔 2s 
输出 3
... 循环

方法一

思路：await + Promise

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const helper = function (i) {
  console.log(i);
  return new Promise(function (resolve) {
    setTimeout(function () {
      resolve();
    }, i * 1000);
  });
};

const fn = async function () {
  const range = 4;
  let cur = 0;
  while (true) {
    cur = ++cur % 4 || 1;
    await helper(cur);
  }
};
fn();

方法二

思路：for await…of + generator

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var iterable = {
  [Symbol.asyncIterator]() {
    const range = 4;
    return {
      i: 0,
      next() {
        this.i = ++this.i % range || 1;
        console.log(this.i);
        return new Promise((resolve) => {
          setTimeout(() => {
            resolve({ done: false });
          }, this.i * 1000);
        });
      },
    };
  },
};

(async function () {
  for await (let _ of iterable) {
  }
})();