tiny xhr-ajax

javascript

const tinyAjax = function tinyAjax(config) {
  return new Promise((resolve, reject) => {
    let request = new XMLHttpRequest()
    request.open(config.method.toUpperCase(), config.url, true)
    request.timeout = config.timeout || 60000
    // Listen for ready state
    request.onreadystatechange = function handleLoad() {
      if (!request || (request.readyState !== 4)) {
        return;
      }
  
      // The request errored out and we didn't get a response, this will be
      // handled by onerror instead
      // With one exception: request that using file: protocol, most browsers
      // will return status as 0 even though it's a successful request
      if (request.status === 0 && !(request.responseURL && request.responseURL.indexOf('file:') === 0)) {
        return;
      }
  
      let responseData = !config.responseType || config.responseType === 'text' ? request.responseText : request.response;
      if (config.responseType === 'json') {
        try {
          responseData = JSON.parse(responseData)
        } catch (error) {
          reject(error, config, request)
        }
      }
      resolve(responseData, config, request)
      // Clean up request
      request = null;
    }
    // Handle low level network errors
    request.onerror = function handleError() {
      // Real errors are hidden from us by the browser
      // onerror should only fire if it's a network error
      reject('Network Error', config, request);

      // Clean up request
      request = null;
    };

    // Handle timeout
    request.ontimeout = function handleTimeout() {
      reject(`timeout of ${config.timeout} ms exceeded`, config, request);

      // Clean up request
      request = null;
    };
  })
}