var WebDemon = new (function () { var TIMEOUT = 150; // timeout in seconds, after which script will auto-reconnect var T = this; var onrecieve = null; // function is called on WebDemon.rcv(...); var $ = function(id){ return document.getElementById(id); }; var next_timeout = null; var backend_src = null; T.reconnect = function() { $('webdemon_iframe').src = backend_src + '&' + Math.random(); next_timeout = setTimeout(T.reconnect, TIMEOUT * 1000); } T.register = function(backend, onrcv_func) { if(!document.body) { throw "WebDemon.register() cannot be called directly from or without on the page"; } if($('webdemon_iframe')) { throw "Only one WebDemon instance is supported"; } onrecieve = onrcv_func; var el = document.createElement('IFRAME'); var styles = { position: 'absolute', top: '0px', left: '0px', visibility: 'hidden' }; for(var k in styles) el.style[k] = styles[k]; backend_src = el.src = backend + (backend.indexOf('?') >= 0 ? '&' : '?') + 'InstanceId=0'; el.width = 1; el.height = 1; el.id = 'webdemon_iframe'; document.body.appendChild(el); //document.body.innerHTML = ''; next_timeout = setTimeout(T.reconnect, TIMEOUT * 1000); }; T.ping = function() { clearTimeout(next_timeout); next_timeout = setTimeout(T.reconnect, TIMEOUT * 1000); }; T.rcv = function(iid /* instance id */, data) { if(!onrecieve) { throw "Recieve event registered, but is not available"; } T.ping(); onrecieve(data); }; })();