Making Asynchronous HTTP Requests with request.post() in Node.js

The request.post() method in Node.js provides a convenient way to make HTTP POST requests. However, by default it is a synchronous method that will block the event loop while the request is in progress. Here are some techniques for making request.post() asynchronous and non-blocking:

Use a Callback

The easiest way is to provide a callback function as the last argument to request.post(). This callback will be invoked once the request finishes:

request.post(url, data, callback);

function callback(error, response, body) {
  if (!error && response.statusCode === 200) {
    // Request succeeded
  }
} 

This allows other code to run while the request is in progress, avoiding blocking the event loop.

Return a Promise

Another option is to wrap the request.post() call in a Promise:

function makeRequest() {
  return new Promise((resolve, reject) => {
    request.post(url, data, (error, response, body) => {
      if (error) return reject(error);
      resolve(response);
    });
  });
}

makeRequest()
  .then(handleResponse)
  .catch(handleError);

This provides a clean interface using async/await.

Use Async Library

The async library has useful abstractions like async.parallel() to run multiple asynchronous operations concurrently:

async.parallel([
  function(callback) {
    request.post(url1, callback);
  },
  function(callback) {
    request.post(url2, callback);
  }
], function(err, results) {
  // all requests completed
});

This allows coordinating multiple requests avoiding nested callbacks.

In summary, Node.js enables asynchronous I/O out of the box if you structure your code properly. Using callbacks, promises or helper libraries like async unlocks this powerful capability for non-blocking HTTP requests.