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/**
* Module requirements.
*/
var Polling = require('./polling');
var inherit = require('component-inherit');
/**
* Module exports.
*/
module.exports = JSONPPolling;
/**
* Cached regular expressions.
*/
var rNewline = /\n/g;
var rEscapedNewline = /\\n/g;
/**
* Global JSONP callbacks.
*/
var callbacks;
/**
* Noop.
*/
function empty () { }
/**
* JSONP Polling constructor.
*
* @param {Object} opts.
* @api public
*/
function JSONPPolling (opts) {
Polling.call(this, opts);
this.query = this.query || {};
// define global callbacks array if not present
// we do this here (lazily) to avoid unneeded global pollution
if (!callbacks) {
// we need to consider multiple engines in the same page
if (!global.___eio) global.___eio = [];
callbacks = global.___eio;
}
// callback identifier
this.index = callbacks.length;
// add callback to jsonp global
var self = this;
callbacks.push(function (msg) {
self.onData(msg);
});
// append to query string
this.query.j = this.index;
// prevent spurious errors from being emitted when the window is unloaded
if (global.document && global.addEventListener) {
global.addEventListener('beforeunload', function () {
if (self.script) self.script.onerror = empty;
}, false);
}
}
/**
* Inherits from Polling.
*/
inherit(JSONPPolling, Polling);
/*
* JSONP only supports binary as base64 encoded strings
*/
JSONPPolling.prototype.supportsBinary = false;
/**
* Closes the socket.
*
* @api private
*/
JSONPPolling.prototype.doClose = function () {
if (this.script) {
this.script.parentNode.removeChild(this.script);
this.script = null;
}
if (this.form) {
this.form.parentNode.removeChild(this.form);
this.form = null;
this.iframe = null;
}
Polling.prototype.doClose.call(this);
};
/**
* Starts a poll cycle.
*
* @api private
*/
JSONPPolling.prototype.doPoll = function () {
var self = this;
var script = document.createElement('script');
if (this.script) {
this.script.parentNode.removeChild(this.script);
this.script = null;
}
script.async = true;
script.src = this.uri();
script.onerror = function (e) {
self.onError('jsonp poll error', e);
};
var insertAt = document.getElementsByTagName('script')[0];
if (insertAt) {
insertAt.parentNode.insertBefore(script, insertAt);
} else {
(document.head || document.body).appendChild(script);
}
this.script = script;
var isUAgecko = 'undefined' !== typeof navigator && /gecko/i.test(navigator.userAgent);
if (isUAgecko) {
setTimeout(function () {
var iframe = document.createElement('iframe');
document.body.appendChild(iframe);
document.body.removeChild(iframe);
}, 100);
}
};
/**
* Writes with a hidden iframe.
*
* @param {String} data to send
* @param {Function} called upon flush.
* @api private
*/
JSONPPolling.prototype.doWrite = function (data, fn) {
var self = this;
if (!this.form) {
var form = document.createElement('form');
var area = document.createElement('textarea');
var id = this.iframeId = 'eio_iframe_' + this.index;
var iframe;
form.className = 'socketio';
form.style.position = 'absolute';
form.style.top = '-1000px';
form.style.left = '-1000px';
form.target = id;
form.method = 'POST';
form.setAttribute('accept-charset', 'utf-8');
area.name = 'd';
form.appendChild(area);
document.body.appendChild(form);
this.form = form;
this.area = area;
}
this.form.action = this.uri();
function complete () {
initIframe();
fn();
}
function initIframe () {
if (self.iframe) {
try {
self.form.removeChild(self.iframe);
} catch (e) {
self.onError('jsonp polling iframe removal error', e);
}
}
try {
// ie6 dynamic iframes with target="" support (thanks Chris Lambacher)
var html = '<iframe src="javascript:0" name="' + self.iframeId + '">';
iframe = document.createElement(html);
} catch (e) {
iframe = document.createElement('iframe');
iframe.name = self.iframeId;
iframe.src = 'javascript:0';
}
iframe.id = self.iframeId;
self.form.appendChild(iframe);
self.iframe = iframe;
}
initIframe();
// escape \n to prevent it from being converted into \r\n by some UAs
// double escaping is required for escaped new lines because unescaping of new lines can be done safely on server-side
data = data.replace(rEscapedNewline, '\\\n');
this.area.value = data.replace(rNewline, '\\n');
try {
this.form.submit();
} catch (e) {}
if (this.iframe.attachEvent) {
this.iframe.onreadystatechange = function () {
if (self.iframe.readyState === 'complete') {
complete();
}
};
} else {
this.iframe.onload = complete;
}
};
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