strata/lib/response.js

A modular, streaming HTTP server

var utils = require('./utils');

module.exports = Response;

/**
 * Provides a convenient interface for setting various properties of the
 * response.
 *
 *   var res = new Response(body, headers, status);
 *   res.addHeader("Content-Length", "123");
 *   res.setCookie("cookieName", "cookieValue");
 *   res.send(callback);
 */
function Response(body, headers, status) {
  if (!(this instanceof Response)) {
    return new Response(body, headers, status);
  }

  this.body = body || '';
  this.headers = headers || {};
  this.status = status || 200;
}

/**
 * Sugar for sending this response using the given callback.
 */
Response.prototype.send = function (callback) {
  callback(this.status, this.headers, this.body);
};

/**
 * Returns true if this response is empty, false otherwise.
 * Note: This is determined by the status code, not the actual body.
 */
Response.prototype.__defineGetter__('empty', function () {
  if (this.body === '') {
    return true;
  }

  return utils.isEmptyBodyStatus(this.status);
});

/**
 * Returns true if this response uses chunked transfer encoding.
 */
Response.prototype.__defineGetter__('chunked', function () {
  return this.transferEncoding === 'chunked';
});

/**
 * Sets the value of the header with the given name.
 */
Response.prototype.setHeader = function (name, value) {
  name = utils.canonicalHeaderName(name);

  if (value instanceof Date) {
    value = value.toGMTString();
  } else if (typeof value !== 'string') {
    value = value.toString();
  }

  this.headers[name] = value;
};

/**
 * Removes the header with the given name.
 */
Response.prototype.removeHeader = function (name) {
  name = utils.canonicalHeaderName(name);
  delete this.headers[name];
};

/**
 * Returns true if this response has a header with the given name.
 */
Response.prototype.hasHeader = function (name) {
  name = utils.canonicalHeaderName(name);
  return (name in this.headers);
};

/**
 * Adds the given value to the header with the given name.
 */
Response.prototype.addHeader = function (name, value) {
  name = utils.canonicalHeaderName(name);

  if (this.headers[name]) {
    value = [this.headers[name], value].join('\n');
  }

  this.headers[name] = value;
};

/**
 * Adds a cookie to the Set-Cookie header with the given name and value.
 * The value should be a string containing the value of the cookie or may be
 * an object with any of the following properties:
 *
 *   - value    The value of the cookie
 *   - domain   The domain
 *   - path     The path
 *   - expires    Should be a Date object
 *   - secure   Should be a boolean
 *   - httpOnly   Should be a boolean
 */
Response.prototype.setCookie = function (name, value) {
  value = value || {};

  if (typeof value === 'string') {
    value = { value: value };
  }

  var cookie = encodeURIComponent(name) + '=';

  if (value.value) cookie += encodeURIComponent(value.value);
  if (value.domain) cookie += '; domain=' + value.domain;
  if (value.path) cookie += '; path=' + value.path;
  if (value.expires) cookie += '; expires=' + value.expires.toUTCString();
  if (value.secure) cookie += '; secure';
  if (value.httpOnly) cookie += '; HttpOnly';

  var setCookie = this.headers['Set-Cookie'];

  if (typeof setCookie === 'string' && setCookie != '') {
    cookie = [setCookie, cookie].join('\n');
  }

  this.headers['Set-Cookie'] = cookie;
};

/**
 * Removes the cookie with the given name and value. See Response#addCookie
 * for more information on the value argument.
 * Note: This will both expire the cookie and remove any value that it has
 * in the response.
 */
Response.prototype.removeCookie = function (name, value) {
  value = value || {};

  if (typeof value === 'string') {
    value = { value: value };
  }

  var setCookie = this.headers['Set-Cookie'],
    cookies;

  if (typeof setCookie === 'string') {
    cookies = setCookie.split('\n');
  } else {
    cookies = [];
  }

  var matcher;
  if (value.domain) {
    matcher = new RegExp('^' + encodeURIComponent(name) + '=.*?domain=' + value.domain);
  } else {
    matcher = new RegExp('^' + encodeURIComponent(name) + '=');
  }

  cookies = cookies.filter(function (c) {
    return !matcher.test(c);
  });

  this.headers['Set-Cookie'] = cookies.join('\n');

  value.expires = new Date(0); // Expire the cookie.
  delete value.value; // Remove the cookie value.

  this.setCookie(name, value);
};

/**
 * Sets the Location header to redirect the client to the given location. The
 * status defaults to 302.
 */
Response.prototype.redirect = function (location, status) {
  this.location = location;
  this.status = status || 302;
};

/**
 * An array of all HTTP response header names.
 */
Response.headers = [
  'Accept-Ranges',
  'Age',
  'Allow',
  'Cache-Control',
  'Connection',
  'Content-Encoding',
  'Content-Language',
  'Content-Length',
  'Content-Location',
  'Content-MD5',
  'Content-Disposition',
  'Content-Range',
  'Content-Type',
  'Date',
  'ETag',
  'Expires',
  'Last-Modified',
  'Link',
  'Location',
  'P3P',
  'Pragma',
  'Proxy-Authenticate',
  'Refresh',
  'Retry-After',
  'Server',
  'Set-Cookie',
  'Strict-Transport-Security',
  'Trailer',
  'Transfer-Encoding',
  'Vary',
  'Via',
  'Warning',
  'WWW-Authenticate'
];

/**
 * Define convenient getters/setters for all response headers using the
 * camel-cased version of the HTTP header name, e.g.:
 *
 * Host => host
 * Last-Modified => lastModified
 */
Response.headers.forEach(function (headerName) {
  var propertyName = utils.propertyName(headerName);

  if (propertyName in Response.prototype) {
    return;
  }

  Object.defineProperty(Response.prototype, propertyName, {
    enumerable: true,
    set: function (value) {
      this.setHeader(headerName, value);
    },
    get: function () {
      return this.headers[headerName];
    }
  });
});