Question

How can I make an HTTP request from within Node.js or Express.js? I need to connect to another service. I am hoping the call is asynchronous and that the callback contains the remote server’s response.

Answer 1

Here is a snippet of some code from a sample of mine. It’s asynchronous and returns a JSON object. It can do any form of GET request.

Note that there are more optimal ways (just a sample) – for example, instead of concatenating the chunks you put into an array and join it etc… Hopefully, it gets you started in the right direction:

const http = require('http');
const https = require('https');

/**
 * getJSON:  RESTful GET request returning JSON object(s)
 * @param options: http options object
 * @param callback: callback to pass the results JSON object(s) back
 */

module.exports.getJSON = (options, onResult) => {
  console.log('rest::getJSON');
  const port = options.port == 443 ? https : http;

  let output = '';

  const req = port.request(options, (res) => {
    console.log(`${options.host} : ${res.statusCode}`);
    res.setEncoding('utf8');

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

    res.on('end', () => {
      let obj = JSON.parse(output);

      onResult(res.statusCode, obj);
    });
  });

  req.on('error', (err) => {
    // res.send('error: ' + err.message);
  });

  req.end();
};

It’s called by creating an options object like:

const options = {
  host: 'somesite.com',
  port: 443,
  path: '/some/path',
  method: 'GET',
  headers: {
    'Content-Type': 'application/json'
  }
};

And providing a callback function.

For example, in a service, I require the REST module above and then do this:

rest.getJSON(options, (statusCode, result) => {
  // I could work with the resulting HTML/JSON here. I could also just return it
  console.log(`onResult: (${statusCode})\n\n${JSON.stringify(result)}`);

  res.statusCode = statusCode;

  res.send(result);
});

UPDATE

If you’re looking for async/await (linear, no callback), promises, compile time support and intellisense, we created a lightweight HTTP and REST client that fits that bill:

Microsoft typed-rest-client