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node_modules/sockjs-client/lib/info-receiver.js 2.17 KB
aaac7fed   liuqimichale   add
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  'use strict';
  
  var EventEmitter = require('events').EventEmitter
    , inherits = require('inherits')
    , urlUtils = require('./utils/url')
    , XDR = require('./transport/sender/xdr')
    , XHRCors = require('./transport/sender/xhr-cors')
    , XHRLocal = require('./transport/sender/xhr-local')
    , XHRFake = require('./transport/sender/xhr-fake')
    , InfoIframe = require('./info-iframe')
    , InfoAjax = require('./info-ajax')
    ;
  
  var debug = function() {};
  if (process.env.NODE_ENV !== 'production') {
    debug = require('debug')('sockjs-client:info-receiver');
  }
  
  function InfoReceiver(baseUrl, urlInfo) {
    debug(baseUrl);
    var self = this;
    EventEmitter.call(this);
  
    setTimeout(function() {
      self.doXhr(baseUrl, urlInfo);
    }, 0);
  }
  
  inherits(InfoReceiver, EventEmitter);
  
  // TODO this is currently ignoring the list of available transports and the whitelist
  
  InfoReceiver._getReceiver = function(baseUrl, url, urlInfo) {
    // determine method of CORS support (if needed)
    if (urlInfo.sameOrigin) {
      return new InfoAjax(url, XHRLocal);
    }
    if (XHRCors.enabled) {
      return new InfoAjax(url, XHRCors);
    }
    if (XDR.enabled && urlInfo.sameScheme) {
      return new InfoAjax(url, XDR);
    }
    if (InfoIframe.enabled()) {
      return new InfoIframe(baseUrl, url);
    }
    return new InfoAjax(url, XHRFake);
  };
  
  InfoReceiver.prototype.doXhr = function(baseUrl, urlInfo) {
    var self = this
      , url = urlUtils.addPath(baseUrl, '/info')
      ;
    debug('doXhr', url);
  
    this.xo = InfoReceiver._getReceiver(baseUrl, url, urlInfo);
  
    this.timeoutRef = setTimeout(function() {
      debug('timeout');
      self._cleanup(false);
      self.emit('finish');
    }, InfoReceiver.timeout);
  
    this.xo.once('finish', function(info, rtt) {
      debug('finish', info, rtt);
      self._cleanup(true);
      self.emit('finish', info, rtt);
    });
  };
  
  InfoReceiver.prototype._cleanup = function(wasClean) {
    debug('_cleanup');
    clearTimeout(this.timeoutRef);
    this.timeoutRef = null;
    if (!wasClean && this.xo) {
      this.xo.close();
    }
    this.xo = null;
  };
  
  InfoReceiver.prototype.close = function() {
    debug('close');
    this.removeAllListeners();
    this._cleanup(false);
  };
  
  InfoReceiver.timeout = 8000;
  
  module.exports = InfoReceiver;