Cannot catch error with try-catch block inside async function-CodePudding

I'm trying to incorporate a try-catch block into an async function. But I cannot seem to catch an error with status code 400 with the code I have written below.

const run = async () => {
  const response = await client.lists.addListMember(listId, {
    email_address: email,
    status: "subscribed",
    merge_fields: {
      firstName: firstName,
      lastName: lastName
    }
  });
  try {
    res.sendFile(__dirname   "/success.html");
  } catch (err) {
    res.sendFile(__dirname   "/failure.html");
  }
};
run();

I found that altering the "run" function instead of incorporating the try-catch block into the async function and removing the try-catch block as the following works, but why? What is the difference between those two codes?

app.post("/", function(req, res) {
  const firstName = req.body.fname;
  const lastName = req.body.lname;
  const email = req.body.email;
  client.setConfig({
    apiKey: "*****-us10",
    server: "us10",
  });
  const listId = "****";
  const run = async () => {
    const response = await client.lists.addListMember(listId, {
      email_address: email,
      status: "subscribed",
      merge_fields: {
        firstName: firstName,
        lastName: lastName
      }
    });

    res.sendFile(__dirname   "/success.html");
  };

  run().catch(e =>   res.sendFile(__dirname   "/failure.html"));

I am following the Mailchimp API documentation.

CodePudding user response：

The issue is that in order to catch the possible rejection returned by await client.lists.addListMember(...) that code needs to be inside the try block - since catch only handles errors inside the associated try block

i.e.

try {
   code that could throw an erro
} catch(err) {
   handle error thrown in the try
}

So, it's as simple as moving the try { to include the await .... code

const run = async () => {
  try {
    const response = await client.lists.addListMember(listId, {
      email_address: email,
      status: "subscribed",
      merge_fields: {
        firstName: firstName,
        lastName: lastName
      }
    });
    res.sendFile(__dirname   "/success.html");
  } catch (err) {
    res.sendFile(__dirname   "/failure.html");
  }
};
run();

CodePudding user response：

You have try {} catch {} in the wrong spot, it shouldn't just go under "res.sendFile();", it should go under both await client.lists.addListMember:

const run = async () => {
  try {
    const response = await client.lists.addListMember(listId, {
      email_address: email,
      status: "subscribed",
      merge_fields: {
        firstName: firstName,
        lastName: lastName
      }
    });
    await res.sendFile(__dirname   "/success.html");
  } catch (err) {
    await res.sendFile(__dirname   "/failure.html");
  }
};
run();