Asynchronous XMLHttpRequest abstraction

xhr.js

/**
 * Asynchronous XMLHttpRequest abstraction.
 * @author Nurudin Imsirovic <[email protected]>
 * @param {string} requestMethod - HTTP Request Method [GET, POST, PUT, DELETE, HEAD, OPTIONS, PATCH]
 * @param {string} requestSource - URL or relative path to a resource
 * @param {string} requestData - Data to be sent (only for POST method)
 * @param {function} callback - Callback function for handling the response
 * @param {string|null} requestUsername - HTTP Basic Auth Username (default `null`)
 * @param {string|null} requestPassword - HTTP Basic Auth Password (default `null`)
 * @throws {Error} Throws an error if XMLHttpRequest is not supported or if the callback is not a function.
 */
function xhr(
  requestMethod = 'GET',
  requestSource = '',
  requestData = '',
  callback,
  requestUsername = null,
  requestPassword = null
) {
  // Check for XMLHttpRequest support
  if (!window.XMLHttpRequest) {
    throw new Error('XMLHttpRequest is not supported');
  }

  // Validate callback function
  if (typeof callback !== 'function') {
    throw new Error('callback must be a function');
  }

  // Supported request methods
  const supportedMethods = ['GET', 'POST', 'PUT', 'DELETE', 'HEAD', 'OPTIONS', 'PATCH'];
  requestMethod = requestMethod.trim().toUpperCase();

  // Validate request method
  if (!supportedMethods.includes(requestMethod)) {
    throw new Error(`Request method "${requestMethod}" is not supported`);
  }

  // Create XHR instance
  const xhrInstance = new XMLHttpRequest();
  xhrInstance.responseType = 'text';

  // Set headers for POST requests
  if (requestMethod == 'POST') {
    xhrInstance.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
  }

  // Open request
  xhrInstance.open(requestMethod, requestSource, true, requestUsername, requestPassword);

  // Set up the callback for ready state changes
  xhrInstance.onreadystatechange = function() {
    callback(xhrInstance);
  };

  // Send the request
  xhrInstance.send(requestMethod == 'POST' ? requestData : null);
}