online.js
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function getterSetter(variableParent, variableName, getterFunction, setterFunction) {
if (Object.defineProperty) {
Object.defineProperty(variableParent, variableName, {
get: getterFunction,
set: setterFunction
});
}
else if (document.__defineGetter__) {
variableParent.__defineGetter__(variableName, getterFunction);
variableParent.__defineSetter__(variableName, setterFunction);
}
}
(function (w) {
w.onlinejs = w.onlinejs || {};
//Checks interval can be changed in runtime
w.onLineCheckTimeout = 5000;
//Use window.onLineURL incapsulated variable http://192.168.3.170:81/mobilemode/images/add_wev8.png
w.onlinejs._onLineURL = "/mobilemode/js/online/online.jsp";
w.onlinejs.setOnLineURL = function (newURL) {
w.onlinejs._onLineURL = newURL;
w.onlinejs.getStatusFromNavigatorOnLine();
}
w.onlinejs.getOnLineURL = function () {
return w.onlinejs._onLineURL;
}
getterSetter(w, 'onLineURL', w.onlinejs.getOnLineURL, w.onlinejs.setOnLineURL);
//Verification logic
w.onlinejs.setStatus = function (newStatus) {
w.onlinejs.fireHandlerDependOnStatus(newStatus);
w.onLine = newStatus;
}
w.onlinejs.fireHandlerDependOnStatus = function (newStatus) {
if (newStatus === true && w.onLineHandler !== undefined && (w.onLine !== true || w.onlinejs.handlerFired === false)) {
w.onLineHandler();
}
if (newStatus === false && w.offLineHandler !== undefined && (w.onLine !== false || w.onlinejs.handlerFired === false)) {
w.offLineHandler();
}
w.onlinejs.handlerFired = true;
};
w.onlinejs.startCheck = function () {
setInterval("window.onlinejs.logic.checkConnectionWithRequest(true)", w.onLineCheckTimeout);
}
w.onlinejs.stopCheck = function () {
clearInterval("window.onlinejs.logic.checkConnectionWithRequest(true)", w.onLineCheckTimeout);
}
w.checkOnLine = function () {
w.onlinejs.logic.checkConnectionWithRequest(false);
}
w.onlinejs.getOnLineCheckURL = function () {
return w.onlinejs._onLineURL + '?' + Math.floor(Math.random() * 1000000);
}
w.onlinejs.getStatusFromNavigatorOnLine = function () {
if (w.navigator.onLine !== undefined) {
w.onlinejs.setStatus(w.navigator.onLine);
} else {
w.onlinejs.setStatus(true);
}
}
//Network transport layer
var xmlhttp = new XMLHttpRequest();
w.onlinejs.isXMLHttp = function () {
return "withCredentials" in xmlhttp;
}
w.onlinejs.isXDomain = function () {
return typeof XDomainRequest != "undefined";
}
//For IE we use XDomainRequest and sometimes it uses a bit different logic, so adding decorator for this
w.onlinejs.XDomainLogic = {
init: function () {
xmlhttp = new XDomainRequest();
xmlhttp.onerror = function () {
xmlhttp.status = 404;
w.onlinejs.processXmlhttpStatus();
}
xmlhttp.ontimeout = function () {
xmlhttp.status = 404;
w.onlinejs.processXmlhttpStatus();
}
},
onInternetAsyncStatus: function () {
try {
xmlhttp.status = 200;
w.onlinejs.processXmlhttpStatus();
} catch (err) {
w.onlinejs.setStatus(false);
}
},
checkConnectionWithRequest: function (async) {
xmlhttp.onload = w.onlinejs.logic.onInternetAsyncStatus;
var url = w.onlinejs.getOnLineCheckURL();
xmlhttp.open("GET", url);
w.onlinejs.tryToSend(xmlhttp);
}
}
//Another case for decoration is XMLHttpRequest
var timeoutId;
w.onlinejs.XMLHttpLogic = {
init: function () {
},
onInternetAsyncStatus: function () {
if (xmlhttp.readyState == 1) { //open
timeoutId = setTimeout(function(){
w.onlinejs.setStatus(false);
}, 3000);
}
if (xmlhttp.readyState == 2) { //send
if(timeoutId){
clearTimeout(timeoutId);
}
}
if (xmlhttp.readyState === 4) {
try {
w.onlinejs.processXmlhttpStatus();
} catch (err) {
w.onlinejs.setStatus(false);
}
}
},
checkConnectionWithRequest: function (async) {
if (async) {
xmlhttp.onreadystatechange = w.onlinejs.logic.onInternetAsyncStatus;
} else {
xmlhttp.onreadystatechange = undefined;
}
var url = w.onlinejs.getOnLineCheckURL();
xmlhttp.open("HEAD", url, async);
w.onlinejs.tryToSend(xmlhttp);
if (async === false) {
w.onlinejs.processXmlhttpStatus();
return w.onLine;
}
}
}
if (w.onlinejs.isXDomain()) {
w.onlinejs.logic = w.onlinejs.XDomainLogic;
} else {
w.onlinejs.logic = w.onlinejs.XMLHttpLogic;
}
w.onlinejs.processXmlhttpStatus = function () {
var tempOnLine = w.onlinejs.verifyStatus(xmlhttp.status);
w.onlinejs.setStatus(tempOnLine);
}
w.onlinejs.verifyStatus = function (status) {
return status === 200;
}
w.onlinejs.tryToSend = function (xmlhttprequest) {
try {
xmlhttprequest.send();
} catch(e) {
w.onlinejs.setStatus(false);
}
}
//Events handling
w.onlinejs.addEvent = function (obj, type, callback) {
if (window.attachEvent) {
obj.attachEvent('on' + type, callback);
} else {
obj.addEventListener(type, callback);
}
}
w.onlinejs.addEvent(w, 'load', function () {
w.onlinejs.fireHandlerDependOnStatus(w.onLine);
});
w.onlinejs.addEvent(w, 'online', function () {
window.onlinejs.logic.checkConnectionWithRequest(true);
})
w.onlinejs.addEvent(w, 'offline', function () {
window.onlinejs.logic.checkConnectionWithRequest(true);
})
w.onlinejs.getStatusFromNavigatorOnLine();
w.onlinejs.logic.init();
w.checkOnLine();
w.onlinejs.startCheck();
w.onlinejs.handlerFired = false;
})(window);