使用p-wait-for轮询http端点UnhandledPromiseRejectionWarning：TypeError：返回布尔值的预期条件

Question

我有以下代码，使用p-wait-for轮询http端点

const pWaitFor = require('p-wait-for');
const rp = require('request-promise-native');

const options = {
    method: 'GET',
    simple: false,
    resolveWithFullResponse: true,
    url: 'https://httpbin.org/json1'
};
const waitOpts = {interval: 15};

(async () => {
    await pWaitFor(rp(options), waitOpts);
    console.log('done calling');
})();

我收到了错误

(node:36125) UnhandledPromiseRejectionWarning: TypeError: Expected condition to return a boolean
    at Promise.resolve.then.then.value (node_modules/p-wait-for/index.js:16:13)
    at <anonymous>
    at process._tickCallback (internal/process/next_tick.js:188:7)
    at Function.Module.runMain (module.js:695:11)
    at startup (bootstrap_node.js:191:16)
    at bootstrap_node.js:612:3
(node:36125) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:36125) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

目的是每15秒继续轮询https://httpbin.org/json1端点。它应该无限期地继续运行，因为它返回404，请求 - 承诺变成被拒绝的承诺。

Answer 1

通过调用函数返回boolean（true / false），我能够使它工作

const pWaitFor = require('p-wait-for');
const rp = require('request-promise-native');

const options = {
    method: 'GET',
    simple: false,
    resolveWithFullResponse: true,
    url: 'https://httpbin.org/json1'
};
const waitOpts = {interval: 1000};

const invokeApi = async () => {
    const res = await rp(options);
    if (res.statusCode === 200) {
        return true;
    } else {
        return false;
    }
};

(async () => {
    await pWaitFor(invokeApi, waitOpts);
})();

Answer 2

p-wait-for预计会返回boolean（正如您所发现的那样）。

一个比你的answer更好的版本也可以处理任何意外错误，还有4xx和5xx状态代码，见下文：

const pWaitFor = require('p-wait-for');
const rp = require('request-promise-native');

const options = {
  method: 'GET',
  simple: false,
  resolveWithFullResponse: true,
  url: 'https://httpbin.org/json1'
};
const waitOpts = {interval: 1000};

const invokeApi = async () => {
  try {
  await rp(options);
  return true;
  } catch (_) {
    // non 200 http status
    return false
  }
};

(async () => {
  await pWaitFor(invokeApi, waitOpts);
})();