Every time I attempt to execute this piece of code in "node.js", an error pops up

Question

Every time I attempt to execute this piece of code in "node.js", an error pops up

const express = require('express');
const request = require('request');
const bodyParser = require('body-parser');
const https = require('https');
const app = express();

app.use(express.static('public'));
app.use(bodyParser.urlencoded({extended: true}));
app.get('/', function(req, res){
  res.sendFile(__dirname + "/signup.html");
});
app.post('/', function(req,res){
  const firstName = req.body.fName;
  const lastName = req.body.lName;
  const email = req.body.email;
  const data = {
    members: [
      {
        email_address:  email,
        status: "subscribed",
        merge_fields: {
          FNAME: firstName,
          LNAME: lastName
        }
      } 
    ]
  };

  const jsonData = JSON.stringify(data);
  const url ="https://us18.api.mailchimp.com/3.0/lists/081d03d860";
  const options ={
    method: "POST",
    auth: "mick:2c775770a96a720b8c492df7974840d3-us18"
  }

  const apiRequest = https.request(url, options, function(response) {
    if (response.statusCode === 200){
      response.send('Successfully subscribed');
    } else {
      response.send('There was an error with signing up, please try again');
    }

    response.on('data', function(data){
      console.log(JSON.parse(data));
    });
  });

  apiRequest.write(jsonData);
  apiRequest.end();
});

app.listen(3000, function(){
  console.log('Server is running on port 3000');
});

I am working on a project using Node.js to create a newsletter sign up page that interacts with the MailChimp API. However, when I run my code in Node.js, I keep encountering the following error message. It appears that there is an issue with the event listener argument not being a function. Can someone assist me with resolving this problem?

TypeError: "listener" argument must be a function
    at ClientRequest.once (events.js:340:11)
    at new ClientRequest (_http_client.js:164:10)
    at Object.request (http.js:38:10)
    at Object.request (https.js:239:15)
    at C:\Users\Desmond\Desktop\Web Development\Newsletter-Singup\app.js:40:24
    at Layer.handle [as handle_request] (C:\Users\Desmond\Desktop\Web Development\Newsletter-Singup\node_modules\express\lib\router\layer.js:95:5)
    at next (C:\Users\Desmond\Desktop\Web Development\Newsletter-Singup\node_modules\express\lib\router\route.js:137:13)
    at Route.dispatch (C:\Users\Desmond\Desktop\Web Development\Newsletter-Singup\node_modules\express\lib\router\route.js:112:3)
    at Layer.handle [as handle_request] (C:\Users\Desmond\Desktop\Web Development\Newsletter-Singup\node_modules\express\lib\router\layer.js:95:5)
    at C:\Users\Desmond\Desktop\Web Development\Newsletter-Singup\node_modules\express\lib\router\index.js:281:22

javascript node.js express

Answer 1

Answer №1

While reviewing the documentation for the 'https' module, I noticed that the two available arguments are:

request(url, options)
request(options, callback)

Would you consider updating your code to reflect this format?

app.post('/', function(req, res) {
    const firstName = req.body.fName;
    const lastName = req.body.lName;
    const email = req.body.email;

    const data = {
        members: [{
                email_address: email,
                status: "subscribed",
                merge_fields: {
                    FNAME: firstName,
                    LNAME: lastName
                }
            }
        ]
    };

    const jsonData = JSON.stringify(data);

    const options = {
        hostname: 'us18.api.mailchimp.com',
        path: "/3.0/lists/081d03d860",
        method: "POST",
        auth: "mick:2c775770a96a720b8c492df7974840d3-us18"
    }

    const request = https.request(options, function(response) {
        if (response.statusCode === 200) {
            response.send('Successfully subscribed');

        } else {
            response.send('There was an error with signing up, please try again');
        }

        response.on('data', function(data) {
            console.log(JSON.parse(data));
        });
    });

    request.write(jsonData); 
    request.end();
});

Answer 2

While reviewing the documentation for the 'https' module, I noticed that the two available arguments are:

request(url, options)
request(options, callback)

Would you consider updating your code to reflect this format?

app.post('/', function(req, res) {
    const firstName = req.body.fName;
    const lastName = req.body.lName;
    const email = req.body.email;

    const data = {
        members: [{
                email_address: email,
                status: "subscribed",
                merge_fields: {
                    FNAME: firstName,
                    LNAME: lastName
                }
            }
        ]
    };

    const jsonData = JSON.stringify(data);

    const options = {
        hostname: 'us18.api.mailchimp.com',
        path: "/3.0/lists/081d03d860",
        method: "POST",
        auth: "mick:2c775770a96a720b8c492df7974840d3-us18"
    }

    const request = https.request(options, function(response) {
        if (response.statusCode === 200) {
            response.send('Successfully subscribed');

        } else {
            response.send('There was an error with signing up, please try again');
        }

        response.on('data', function(data) {
            console.log(JSON.parse(data));
        });
    });

    request.write(jsonData); 
    request.end();
});

Answer 3

Answer №2

When looking at this snippet:

app.post('/', function(req, res) {    // <== Note that the response is named res

You encounter this piece of code:

const request = https.request(options, function(response) {
    if (response.statusCode === 200) {
        response.send('Successfully subscribed');     // <== This part attempts to send a 
                                                      // response to your response which 
                                                      // doesn't add up

    } else {
        response.send('There was an error with signing up, please try again');
    }

The logic in this code seems flawed. You shouldn't invoke response.send() on the http.request response immediately after receiving it. The http request has completed - you made a request and got a response.

Possibly, you intended for that code block to appear like this where you are sending a response from your server back to the original client's request:

const request = https.request(options, function(response) {
    if (response.statusCode === 200) {
        res.send('Successfully subscribed');    // <== here, use res instead to reference
                                                // the response to the original Express
                                                // request/response

    } else {
        res.send('There was an error with signing up, please try again');
    }

Just so you know, the request() library has been deprecated and is not recommended for new code. There are alternative libraries available, you can find some good options here. Personally, I prefer using got() as it is easy to use, fully supports promises (the modern way of handling asynchronous code), and includes all necessary features.

Answer 4

When looking at this snippet:

app.post('/', function(req, res) {    // <== Note that the response is named res

You encounter this piece of code:

const request = https.request(options, function(response) {
    if (response.statusCode === 200) {
        response.send('Successfully subscribed');     // <== This part attempts to send a 
                                                      // response to your response which 
                                                      // doesn't add up

    } else {
        response.send('There was an error with signing up, please try again');
    }

The logic in this code seems flawed. You shouldn't invoke response.send() on the http.request response immediately after receiving it. The http request has completed - you made a request and got a response.

Possibly, you intended for that code block to appear like this where you are sending a response from your server back to the original client's request:

const request = https.request(options, function(response) {
    if (response.statusCode === 200) {
        res.send('Successfully subscribed');    // <== here, use res instead to reference
                                                // the response to the original Express
                                                // request/response

    } else {
        res.send('There was an error with signing up, please try again');
    }

Just so you know, the request() library has been deprecated and is not recommended for new code. There are alternative libraries available, you can find some good options here. Personally, I prefer using got() as it is easy to use, fully supports promises (the modern way of handling asynchronous code), and includes all necessary features.

Every time I attempt to execute this piece of code in "node.js", an error pops up

Answer №1

Answer №2

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