falcor-http-datasource/src/request.js

This package contains falcor components for use in browsers.

'use strict';
var getXMLHttpRequest = require('./getXMLHttpRequest');
var getCORSRequest = require('./getCORSRequest');
var hasOwnProp = Object.prototype.hasOwnProperty;

var noop = function() {};

function Observable() {}

Observable.create = function(subscribe) {
  var o = new Observable();

  o.subscribe = function(onNext, onError, onCompleted) {

    var observer;
    var disposable;

    if (typeof onNext === 'function') {
        observer = {
            onNext: onNext,
            onError: (onError || noop),
            onCompleted: (onCompleted || noop)
        };
    } else {
        observer = onNext;
    }

    disposable = subscribe(observer);

    if (typeof disposable === 'function') {
      return {
        dispose: disposable
      };
    } else {
      return disposable;
    }
  };

  return o;
};

function request(method, options, context) {
  return Observable.create(function requestObserver(observer) {

    var config = {
      method: method || 'GET',
      crossDomain: false,
      async: true,
      headers: {},
      responseType: 'json'
    };

    var xhr,
      isDone,
      headers,
      header,
      prop;

    for (prop in options) {
      if (hasOwnProp.call(options, prop)) {
        config[prop] = options[prop];
      }
    }

    // Add request with Headers
    if (!config.crossDomain && !config.headers['X-Requested-With']) {
      config.headers['X-Requested-With'] = 'XMLHttpRequest';
    }

    // allow the user to mutate the config open
    if (context.onBeforeRequest != null) {
      context.onBeforeRequest(config);
    }

    // create xhr
    try {
      xhr = config.crossDomain ? getCORSRequest() : getXMLHttpRequest();
    } catch (err) {
      observer.onError(err);
    }
    try {
      // Takes the url and opens the connection
      if (config.user) {
        xhr.open(config.method, config.url, config.async, config.user, config.password);
      } else {
        xhr.open(config.method, config.url, config.async);
      }

      // Sets timeout information
      xhr.timeout = config.timeout;

      // Anything but explicit false results in true.
      xhr.withCredentials = config.withCredentials !== false;

      // Fills the request headers
      headers = config.headers;
      for (header in headers) {
        if (hasOwnProp.call(headers, header)) {
          xhr.setRequestHeader(header, headers[header]);
        }
      }

      if (config.responseType) {
        try {
          xhr.responseType = config.responseType;
        } catch (e) {
          // WebKit added support for the json responseType value on 09/03/2013
          // https://bugs.webkit.org/show_bug.cgi?id=73648. Versions of Safari prior to 7 are
          // known to throw when setting the value "json" as the response type. Other older
          // browsers implementing the responseType
          //
          // The json response type can be ignored if not supported, because JSON payloads are
          // parsed on the client-side regardless.
          if (config.responseType !== 'json') {
            throw e;
          }
        }
      }

      xhr.onreadystatechange = function onreadystatechange(e) {
        // Complete
        if (xhr.readyState === 4) {
          if (!isDone) {
            isDone = true;
            onXhrLoad(observer, xhr, e);
          }
        }
      };

      // Timeout
      xhr.ontimeout = function ontimeout(e) {
        if (!isDone) {
          isDone = true;
          onXhrError(observer, xhr, 'timeout error', e);
        }
      };

      // Send Request
      xhr.send(config.data);

    } catch (e) {
      observer.onError(e);
    }
    // Dispose
    return function dispose() {
      // Doesn't work in IE9
      if (!isDone && xhr.readyState !== 4) {
        isDone = true;
        xhr.abort();
      }
    };//Dispose
  });
}

/*
 * General handling of ultimate failure (after appropriate retries)
 */
function _handleXhrError(observer, textStatus, errorThrown) {
  // IE9: cross-domain request may be considered errors
  if (!errorThrown) {
    errorThrown = new Error(textStatus);
  }

  observer.onError(errorThrown);
}

function onXhrLoad(observer, xhr, e) {
  var responseData,
    responseObject,
    responseType;

  // If there's no observer, the request has been (or is being) cancelled.
  if (xhr && observer) {
    responseType = xhr.responseType;
    // responseText is the old-school way of retrieving response (supported by IE8 & 9)
    // response/responseType properties were introduced in XHR Level2 spec (supported by IE10)
    responseData = ('response' in xhr) ? xhr.response : xhr.responseText;

    // normalize IE9 bug (http://bugs.jquery.com/ticket/1450)
    var status = (xhr.status === 1223) ? 204 : xhr.status;

    if (status >= 200 && status <= 399) {
      try {
        if (responseType !== 'json') {
          responseData = JSON.parse(responseData || '');
        }
        if (typeof responseData === 'string') {
          responseData = JSON.parse(responseData || '');
        }
      } catch (e) {
        _handleXhrError(observer, 'invalid json', e);
      }
      observer.onNext(responseData);
      observer.onCompleted();
      return;

    } else if (status === 401 || status === 403 || status === 407) {

      return _handleXhrError(observer, responseData);

    } else if (status === 410) {
      // TODO: Retry ?
      return _handleXhrError(observer, responseData);

    } else if (status === 408 || status === 504) {
      // TODO: Retry ?
      return _handleXhrError(observer, responseData);

    } else {

      return _handleXhrError(observer, responseData || ('Response code ' + status));

    }//if
  }//if
}//onXhrLoad

function onXhrError(observer, xhr, status, e) {
  _handleXhrError(observer, status || xhr.statusText || 'request error', e);
}

module.exports = request;