'use strict';
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var EventEmitter = require('events').EventEmitter
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, inherits = require('inherits')
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, utils = require('../../utils/event')
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, urlUtils = require('../../utils/url')
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, XHR = global.XMLHttpRequest
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;
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var debug = function() {};
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if (process.env.NODE_ENV !== 'production') {
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debug = require('debug')('sockjs-client:browser:xhr');
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}
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function AbstractXHRObject(method, url, payload, opts) {
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debug(method, url);
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var self = this;
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EventEmitter.call(this);
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setTimeout(function () {
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self._start(method, url, payload, opts);
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}, 0);
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}
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inherits(AbstractXHRObject, EventEmitter);
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AbstractXHRObject.prototype._start = function(method, url, payload, opts) {
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var self = this;
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try {
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this.xhr = new XHR();
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} catch (x) {
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// intentionally empty
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}
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if (!this.xhr) {
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debug('no xhr');
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this.emit('finish', 0, 'no xhr support');
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this._cleanup();
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return;
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}
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// several browsers cache POSTs
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url = urlUtils.addQuery(url, 't=' + (+new Date()));
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// Explorer tends to keep connection open, even after the
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// tab gets closed: http://bugs.jquery.com/ticket/5280
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this.unloadRef = utils.unloadAdd(function() {
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debug('unload cleanup');
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self._cleanup(true);
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});
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try {
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this.xhr.open(method, url, true);
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if (this.timeout && 'timeout' in this.xhr) {
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this.xhr.timeout = this.timeout;
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this.xhr.ontimeout = function() {
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debug('xhr timeout');
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self.emit('finish', 0, '');
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self._cleanup(false);
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};
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}
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} catch (e) {
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debug('exception', e);
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// IE raises an exception on wrong port.
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this.emit('finish', 0, '');
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this._cleanup(false);
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return;
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}
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if ((!opts || !opts.noCredentials) && AbstractXHRObject.supportsCORS) {
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debug('withCredentials');
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// Mozilla docs says https://developer.mozilla.org/en/XMLHttpRequest :
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// "This never affects same-site requests."
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this.xhr.withCredentials = true;
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}
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if (opts && opts.headers) {
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for (var key in opts.headers) {
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this.xhr.setRequestHeader(key, opts.headers[key]);
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}
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}
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this.xhr.onreadystatechange = function() {
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if (self.xhr) {
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var x = self.xhr;
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var text, status;
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debug('readyState', x.readyState);
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switch (x.readyState) {
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case 3:
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// IE doesn't like peeking into responseText or status
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// on Microsoft.XMLHTTP and readystate=3
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try {
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status = x.status;
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text = x.responseText;
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} catch (e) {
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// intentionally empty
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}
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debug('status', status);
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// IE returns 1223 for 204: http://bugs.jquery.com/ticket/1450
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if (status === 1223) {
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status = 204;
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}
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// IE does return readystate == 3 for 404 answers.
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if (status === 200 && text && text.length > 0) {
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debug('chunk');
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self.emit('chunk', status, text);
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}
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break;
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case 4:
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status = x.status;
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debug('status', status);
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// IE returns 1223 for 204: http://bugs.jquery.com/ticket/1450
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if (status === 1223) {
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status = 204;
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}
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// IE returns this for a bad port
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// http://msdn.microsoft.com/en-us/library/windows/desktop/aa383770(v=vs.85).aspx
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if (status === 12005 || status === 12029) {
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status = 0;
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}
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debug('finish', status, x.responseText);
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self.emit('finish', status, x.responseText);
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self._cleanup(false);
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break;
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}
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}
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};
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try {
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self.xhr.send(payload);
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} catch (e) {
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self.emit('finish', 0, '');
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self._cleanup(false);
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}
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};
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AbstractXHRObject.prototype._cleanup = function(abort) {
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debug('cleanup');
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if (!this.xhr) {
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return;
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}
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this.removeAllListeners();
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utils.unloadDel(this.unloadRef);
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// IE needs this field to be a function
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this.xhr.onreadystatechange = function() {};
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if (this.xhr.ontimeout) {
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this.xhr.ontimeout = null;
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}
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if (abort) {
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try {
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this.xhr.abort();
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} catch (x) {
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// intentionally empty
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}
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}
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this.unloadRef = this.xhr = null;
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};
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AbstractXHRObject.prototype.close = function() {
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debug('close');
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this._cleanup(true);
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};
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AbstractXHRObject.enabled = !!XHR;
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// override XMLHttpRequest for IE6/7
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// obfuscate to avoid firewalls
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var axo = ['Active'].concat('Object').join('X');
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if (!AbstractXHRObject.enabled && (axo in global)) {
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debug('overriding xmlhttprequest');
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XHR = function() {
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try {
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return new global[axo]('Microsoft.XMLHTTP');
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} catch (e) {
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return null;
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}
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};
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AbstractXHRObject.enabled = !!new XHR();
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}
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var cors = false;
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try {
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cors = 'withCredentials' in new XHR();
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} catch (ignored) {
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// intentionally empty
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}
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AbstractXHRObject.supportsCORS = cors;
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module.exports = AbstractXHRObject;
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