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我正在读取.txt文件数据并调用第3 方 api以使用 .txt 文件数据作为参数连续获取更多数据。为此，我正在使用延迟 2 秒的函数运行await Promise.all()withmap()循环setTimeOut()，以便第 3 方 API 获得延迟时间并避免捕获错误。

之后，我将其附加/推送到 json 对象数组。之后将整个写入JSON.stringify(data)文件.json。我希望一切都按顺序进行。但不幸的是，在调试时，我看到的是writeFileSync甚至在我不想要的循环完成之前执行。

这是我正在尝试的代码：

const writeFile = async (obj) => {
  const json = JSON.stringify(obj);
  fs.writeFileSync('/home/deb/Downloads/Twitty-Bird/src/utils/output.json', json, 'utf8')
  return 'completed';
}

export const convertToJSONFile = async () => {
  try {
    let obj = {
      table: []
    };
    const data = fs.readFileSync('/home/deb/Downloads/Twitty-Bird/src/utils/sample.txt', 'utf8');
    if (!data) throw err;
    let splitted = data.toString().split("\n");
    let interval = 2000;
    await Promise.all(splitted.map(async (word, index) => {
      setTimeout(async function () {
        let wordMeaningDetails = await axios({
        method: 'GET',
        url: `https://api.dictionaryapi.dev/api/v2/entries/en/${word}`
        })
        wordMeaningDetails = wordMeaningDetails.data[0].meanings[0].definitions[0]
        obj.table.push({
          word: word, definition: wordMeaningDetails.definition, example: wordMeaningDetails.example
        });
      }, interval);
    }))

    const res = await writeFile(obj);
    console.log(res);
  }
  catch (err) {
    console.log("Error = ", err);
    //convertToJSONFile();
  }
}

convertToJSONFile();

我想用通俗的话完全按顺序排列：

  1. 首先使用 fs.readFileSync 读取所有数据并拆分为数组
  2. 用axios一一执行3rd party api并将所有数据追加到object obj = {}
  3. 然后最后将该 json 数据写入 .json 文件并将其保存在根文件夹中。

更新：我现在正在使用这个更新的代码：

const promiseResponse = await Promise.all(splitted.map(async (word, index) => new Promise((resolve) => {
  setTimeout(async function () {
    let wordMeaningDetails = await findMeaning(word);
    wordMeaningDetails = wordMeaningDetails.data[0].meanings[0].definitions[0]
    obj.table.push({
      word: word, definition: wordMeaningDetails.definition, example: wordMeaningDetails.example
    });
    console.log(word);
    resolve(); // resolve the promise to mark it as "done"
  }, 1000 * index)
})
))

const res = await writeFile(obj);
console.log(res);

因此，在执行整个拆分数组并解决承诺后，它会引发以下错误，而不是执行res = await writeFile(obj). 我不知道为什么会发生。

aa
aardvark
aargh
aback
abacus
abandon
abandoned
abandoning
abandonment
abandons
(node:78808) UnhandledPromiseRejectionWarning: Error: Request failed with status code 404
    at createError (/home/vikas/Downloads/Twitty Bird/node_modules/axios/lib/core/createError.js:16:15)
    at settle (/home/vikas/Downloads/Twitty Bird/node_modules/axios/lib/core/settle.js:17:12)
    at IncomingMessage.handleStreamEnd (/home/vikas/Downloads/Twitty Bird/node_modules/axios/lib/adapters/http.js:293:11)
    at IncomingMessage.emit (events.js:412:35)
    at endReadableNT (internal/streams/readable.js:1334:12)
    at processTicksAndRejections (internal/process/task_queues.js:82:21)
(node:78808) 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(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2)
(node:78808) [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.
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1 回答 1

1

您需要在 map 函数中返回一个 Promise。见下文：

await Promise.all(splitted.map(async (word, index) => ...)));
// You need to return a promise not a anonymous function because the function
// will resolve instantely and is not waiting for your timeout


(async () => {

  await Promise.all([1, 2, 3].map((word, index) => new Promise((resolve) => {
    setTimeout(async function() {
      console.log(word);
      // do your api stuff
      resolve(); // resolve the promise to mark it as "done"
    }, 1000 * index)
  })))
  console.log("done!")

})();

于 2022-02-02T12:30:23.870 回答