如何将异步承诺功能重构为非异步以避免反模式

Question

我正在尝试重构使用反模式的代码，但仍然不明白如何重构这样的东西： 我现在有一个像这样工作的函数：

export async function submit(data) {
  return new Promise(async function(resolve, reject) {
    ...
    let list = await getList();
    ...
    for (let i = 0; i < list.length; i++) {
       let data = await getData(list[i]);
    }
    ...
    for (let i = 0; i < list.length; i++) {
       let response = await uploadFile(list[i]);
    }

我把这个函数称为：

let response = await submit(data);

我了解 new Promise 中的异步功能有问题，但如何解决？

export async function submit(data) {
  return new Promise(async function(resolve, reject) {
  let files = getFiles();

      let prepareUrlsResponse = await prepareUrls(paths);
      if (prepareUrlsResponse.error === true) {
        resolve( { success: false });
      } else {
        let blobs = [];
        for (let i = 0; i < prepareUrlsResponse.data.length; i++) {
          let fileData = await RNFetchBlob.fs.stat(filePath);
          blobs.push(fileData);
        }

        for (let i = 0; i < blobs.length; i++) {
          let item = blobs[i];

          let response = await uploadFile(
            item.url,
            item.blob
          );

          if (response && response.uploadSuccess === false) {
            resolve( { success: false });
            break;
          }
        }
      }


    api.post(
      endpoint,
      data,
      response => {
        if (response.ok) {
          resolve( { success: true, response: response });
        } else {
          resolve( { success: false });
        }
      }
    );
  });
}

Answer 1

完全放下这条线。您的submit 已经是async function，您可以直接在其中使用await。没有必要围绕整个事情创建一个new Promise，你只需要promisfyapi.post调用。您应该将其分解为一个返回承诺的单独函数，并在其上使用await，就像在您正在调用的其他函数上一样。

function postData(url, data) {
  return new Promise(function(resolve, reject) {
//                   ^^^^^^^^ no `async` here!
    api.post(url, data, resolve);
  });
}

export async function submit(data) {
  let files = getFiles();
  let prepareUrlsResponse = await prepareUrls(paths);
  if (prepareUrlsResponse.error === true) {
    return { success: false };
  } else {
    let blobs = [];
    for (let i = 0; i < prepareUrlsResponse.data.length; i++) {
      let fileData = await RNFetchBlob.fs.stat(filePath);
      blobs.push(fileData);
    }

    for (let i = 0; i < blobs.length; i++) {
      let item = blobs[i];
      let response = await uploadFile(
        item.url,
        item.blob
      );

      if (response && response.uploadSuccess === false) {
        return { success: false };
      }
    }
  }

  const response = await postData(endpoint, data);
  if (response.ok) {
    return { success: true, response: response });
  } else {
    return { success: false };
  }
}

您当然可以内联postData 调用并使用const response = await new Promise(…);，但您应该只包装回调部分而不是整个逻辑。