我正在读取.txt文件数据，并调用第三方api以连续使用.txt文件数据作为参数获取更多数据。为此，我使用延迟2秒的setTimeOut()函数运行await Promise.all()和map()循环，以便第三方API获得延迟时间并避免捕获错误。
之后，我将它附加/推送到一个json对象数组中。之后将整个JSON.stringify(data)写入一个.json文件。我希望所有的东西都按顺序排列。但不幸的是，在调试时，我看到writeFileSync甚至在循环完成之前就被执行了，这是我不希望的。
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();
用外行的话来说，我想要的是什么：
- 首先读取所有数据，并使用fs.readFileSync拆分为数组
- 使用axios逐个执行第三方api，并将所有数据附加到对象obj={}
- 最后，将json数据写入.json文件，并将其保存在根文件夹中
更新：我现在正在使用此更新的代码：
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，在执行了整个拆分数组并解决了promise之后，它抛出了以下错误，而不是执行res = await writeFile(obj).我不知道为什么会这样。
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.
您需要在map函数中返回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!")
})();