Question 169035 in Javascript Question posted in
A very good W3school tutorial can be found here.

Can a REST API call POST return data response from a function into another variable in Javascript?

I have the following code that does a POST to an api. I put it in a function and it works and gives me a response of all the data received back for confirmation. But now I want to return the data back from the function to do something else. As seen below, I put a return in the function but it doesn’t actually return anything from the function. What could be wrong?

const https = require('https');
xxx = postNode('Hello world 9999', 'nothing here', '356', '3');
console.log(xxx);

function postNode (title, body, parent, page) {
  
  ...BUNCH OF CODE HERE...
    
  const request = https.request(options, (response) => {
    let data = '';

    response.on('data', (chunk) => {
      data += chunk;
    });

    response.on('end', () => {
      console.log('Response:', data);  <-- This works!
      return data;  <--- This Doesn't work...
    });
  });

  request.on('error', (error) => {
    console.error('Error:', error);
  });

  request.write(postData);
  request.end();

}
Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    You need to make use of Promises and the await function when working with async.

    First you would need to convert your existing function into a Promise to make use of the await functionality.

    Here's the updated code that would work for you:

    const https = require('https');

async function fetchData() {
  try {
    var yyy;
    const data = await postNode('yyyyxxxhello world 9999', 'nothing here', '356', '3');
    yyy = data;
    return yyy; // Return the value of yyy
  } catch (error) {
    console.error(error);
    throw error;
  }
}

fetchData()
  .then((yyy) => {
    console.log(yyy); // Access the value of yyy outside the async function
  })
  .catch((error) => {
    console.error(error);
  });

function postNode(title, body, parent, page) {
  return new Promise((resolve, reject) => {
    // ...BUNCH OF CODE HERE...

    const request = https.request(options, (response) => {
      let data = '';

      response.on('data', (chunk) => {
        data += chunk;
      });

      response.on('end', () => {
        console.log('Response:', data);
        resolve(data);
      });
    });

    request.on('error', (error) => {
      console.error('Error:', error);
      reject(error);
    });

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

  2. 0

    Once you are in asynchronous land, you need to stay there. You can either:

    1. Add callback to your own function, so the caller of your function can pass their callback.
    2. Convert this to promises so you can await the function
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