javascript - 正确捕获异步函数node.js

Question

我的尝试是:

我的 server.js 有以下内容:

const app = express();
app.get('/*', loader(filePath, observer));

我尝试调用的文件有时会加载错误，这些错误会冒出 uncaughtExceptions 并重新启动服务器。我需要以某种方式捕获它

export default (htmlFilePath, observer) => async (req, res) => {
    try {
      .......
      .......
      .......

        const markupStream = renderToNodeStream(
          <Provider store={store}>
            <ConnectedRouter history={history} location={context}>
              <App/>
            </ConnectedRouter>
          </Provider>
        );

        if (context.url) {
          return res.redirect(301, context.url)
        }

        return fs.createReadStream(htmlFilePath)
          .pipe(htmlReplace('#root', markupStream))
          .pipe(replaceStream('__SERVER_DATA__', serialize(store.getState())))
          .pipe(res);
      } catch (err) {
        const errMarkup = renderToNodeStream(
          <Provider store={store}>
            <ConnectedRouter history={history} location={context}>
              <Error500 error={err}/>
            </ConnectedRouter>
          </Provider>
        );

        logger.log({
          level: 'error',
          message: `Rendering ${req.originalUrl} fallback to Error render method`,
          ...{
            errorMessage: err.message,
            stack: err.stack
          }
        });

        return fs.createReadStream(htmlFilePath)
          .pipe(htmlReplace('#root', errMarkup))
          .pipe(res.status(500));
      } finally {
        logger.info(`Request finished ${req.originalUrl} :: ${res.statusCode}`)
        end({ route: path, componentName: componentNames[0], code: res.statusCode })
        logger.profile(profileMsg);
      }
}

正确的做法是什么？在执行 ().catch(err 之前，我的问题是我总是遇到 uncaughtException，它从未进入 try{} 中的 catch > 函数内的 catch{}

Answer 1

使用 async 快速中间件时，为了捕获任何拒绝并将该拒绝传递给快速错误处理程序，您需要一个包装器:

async-handler.js

const asyncHandler = fn => (req, res, next) => {
    return Promise
        .resolve(fn(req, res, next))
        .catch(next);
};

module.exports = asyncHandler;

ssr-stream.js

const ssrStream = (htmlFilePath, observer) => async (req, res) => {
    // If you wrap this middleware with asyncHandler
    // No need try/catch, you can let it bubble up, and it will go to express error middleware
    // Of course you can do it, and handle the custom error here, and let it bubble up for generic errors.
}

export default ssrStream;

index.js

const app = express();
const asyncHandler = require('./async-handler');
const loader = require('./ssr-stream');

// Wrap your async function, with asyncHandler
app.get('/foo', asyncHandler(async(req, res) => {
    throw new Error('Foo'); // This will go to the express error middleware
}));

app.get('/*', asyncHandler(loader(filePath, observer)));

app.use((err, req, res, next) => {

    // Handle the error type, and set the correct status code
    const status = 500;
    res
        .status(status)
        .end(err.message);
});