In my hydbrid app (Phonegap), I am trying to write to localStorage in a very standard way :
window.localStorage.setItem("proDB", JSON.stringify(data));
or
window.localStorage["proDB"] = JSON.stringify(data);
But it doesn't work on Safari on iPad 2 (iOS 7.1).
It doesn't work and the whole app stops.
Here's the userAgent of this ipad :
Can you help me ?
Thanks
Please check whether you have Private Browsing enabled in Safari. In Safari Private Browsing mode, you get a quota of zero. Hence, all calls to localStorage.setItem will throw a quota exceeded error. Personally I think this is a huge mistake by Safari (as so many sites break), but it is what it is so we have to find a way around it. We can do this by:
Detecting whether we have a functional localStorage
Falling back to some replacement if not.
Read on if you want the details :)
1: Detecting a functional local storage
I am currently using this code to detect whether local storage is available, and fall back to a shim if not:
var DB;
try {
var x = '_localstorage_test_' + Date.now();
localStorage.setItem(x, x);
var y = localStorage.getItem(x);
localStorage.removeItem(x);
if (x !== y) {throw new Error();} // check we get back what we stored
DB = localStorage; // all fine
}
catch(e) {
// no localstorage available, use shim
DB = new MemoryStorage('my-app');
}
EDIT: Since writing this I have packaged up the feature detecting code. If you are using NPM you can install storage-available like so:
npm install --save storage-available
then you can use it in your code like this:
if (require('storage-available')('localStorage')) {
// Yay!
}
else {
// Awwww.....
}
2. Fall back to a shim
The easiest way to deal with the issue once we have detected the problem is to fall back to some other object that does not throw errors on every write.
memorystorage is a little library I wrote that follows the Web Storage API but just stores everything in memory. Because it uses the same API, you can use it as a drop-in replacement for localStorage and everything will function fine (though no data will survive page reload). It's Open Source so use as you please.
Background info
For more information on MemoryStorage and this issue in general, read my blog post on this topic: Introducing MemoryStorage.
I have set local storage key values through below logic using swift2.2
let jsStaring = "localStorage.setItem('Key', 'value')"
self.webView.stringByEvaluatingJavaScriptFromString(jsStaring)
Your first setItem example is correct. I don't believe that you can do the second option (localStorage["someKey"] = "someValue") though. Stick with the first one.
You mention hybrid - is it a PhoneGap or some other framework? Where in the app are you calling localStorage.setItem? If PhoneGap, be sure that everything has loaded via onDeviceReady first before trying to access localStorage:
<script type="text/javascript">
// Wait for PhoneGap to load
document.addEventListener("deviceready", onDeviceReady, false);
// PhoneGap is ready
function onDeviceReady() {
window.localStorage.setItem("key", "value");
}
</script>
Also, if the app freezes/stops working, in my experience it's because somewhere in the code you are accessing an object that is undefined. Perhaps try some debugging by checking if localStorage is undefined and logging it? Are you 100% sure that the "setItem" line is where it fails? Console.log is your friend, prove it! :)
if (localStorage === undefined) {
console.log("oops, localStorage not initialized yet.");
}
else {
window.localStorage.setItem("proDB", JSON.stringify(data));
console.log("localStorage available.");
}
Related
This question already has answers here:
Detect the Internet connection is offline?
(22 answers)
Closed 8 years ago.
How do you check if there is an internet connection using jQuery? That way I could have some conditionals saying "use the google cached version of JQuery during production, use either that or a local version during development, depending on the internet connection".
The best option for your specific case might be:
Right before your close </body> tag:
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
<script>window.jQuery || document.write('<script src="js/vendor/jquery-1.10.2.min.js"><\/script>')</script>
This is probably the easiest way given that your issue is centered around jQuery.
If you wanted a more robust solution you could try:
var online = navigator.onLine;
Read more about the W3C's spec on offline web apps, however be aware that this will work best in modern web browsers, doing so with older web browsers may not work as expected, or at all.
Alternatively, an XHR request to your own server isn't that bad of a method for testing your connectivity. Considering one of the other answers state that there are too many points of failure for an XHR, if your XHR is flawed when establishing it's connection then it'll also be flawed during routine use anyhow. If your site is unreachable for any reason, then your other services running on the same servers will likely be unreachable also. That decision is up to you.
I wouldn't recommend making an XHR request to someone else's service, even google.com for that matter. Make the request to your server, or not at all.
What does it mean to be "online"?
There seems to be some confusion around what being "online" means. Consider that the internet is a bunch of networks, however sometimes you're on a VPN, without access to the internet "at-large" or the world wide web. Often companies have their own networks which have limited connectivity to other external networks, therefore you could be considered "online". Being online only entails that you are connected to a network, not the availability nor reachability of the services you are trying to connect to.
To determine if a host is reachable from your network, you could do this:
function hostReachable() {
// Handle IE and more capable browsers
var xhr = new ( window.ActiveXObject || XMLHttpRequest )( "Microsoft.XMLHTTP" );
// Open new request as a HEAD to the root hostname with a random param to bust the cache
xhr.open( "HEAD", "//" + window.location.hostname + "/?rand=" + Math.floor((1 + Math.random()) * 0x10000), false );
// Issue request and handle response
try {
xhr.send();
return ( xhr.status >= 200 && (xhr.status < 300 || xhr.status === 304) );
} catch (error) {
return false;
}
}
You can also find the Gist for that here: https://gist.github.com/jpsilvashy/5725579
Details on local implementation
Some people have commented, "I'm always being returned false". That's because you're probably testing it out on your local server. Whatever server you're making the request to, you'll need to be able to respond to the HEAD request, that of course can be changed to a GET if you want.
Ok, maybe a bit late in the game but what about checking with an online image?
I mean, the OP needs to know if he needs to grab the Google CMD or the local JQ copy, but that doesn't mean the browser can't read Javascript no matter what, right?
<script>
function doConnectFunction() {
// Grab the GOOGLE CMD
}
function doNotConnectFunction() {
// Grab the LOCAL JQ
}
var i = new Image();
i.onload = doConnectFunction;
i.onerror = doNotConnectFunction;
// CHANGE IMAGE URL TO ANY IMAGE YOU KNOW IS LIVE
i.src = 'http://gfx2.hotmail.com/mail/uxp/w4/m4/pr014/h/s7.png?d=' + escape(Date());
// escape(Date()) is necessary to override possibility of image coming from cache
</script>
Just my 2 cents
5 years later-version:
Today, there are JS libraries for you, if you don't want to get into the nitty gritty of the different methods described on this page.
On of these is https://github.com/hubspot/offline. It checks for the connectivity of a pre-defined URI, by default your favicon. It automatically detects when the user's connectivity has been reestablished and provides neat events like up and down, which you can bind to in order to update your UI.
You can mimic the Ping command.
Use Ajax to request a timestamp to your own server, define a timer using setTimeout to 5 seconds, if theres no response it try again.
If there's no response in 4 attempts, you can suppose that internet is down.
So you can check using this routine in regular intervals like 1 or 3 minutes.
That seems a good and clean solution for me.
You can try by sending XHR Requests a few times, and then if you get errors it means there's a problem with the internet connection.
I wrote a jQuery plugin for doing this. By default it checks the current URL (because that's already loaded once from the Web) or you can specify a URL to use as an argument. Always doing a request to Google isn't the best idea because it's blocked in different countries at different times. Also you might be at the mercy of what the connection across a particular ocean/weather front/political climate might be like that day.
http://tomriley.net/blog/archives/111
i have a solution who work here to check if internet connection exist :
$.ajax({
url: "http://www.google.com",
context: document.body,
error: function(jqXHR, exception) {
alert('Offline')
},
success: function() {
alert('Online')
}
})
Sending XHR requests is bad because it could fail if that particular server is down. Instead, use googles API library to load their cached version(s) of jQuery.
You can use googles API to perform a callback after loading jQuery, and this will check if jQuery was loaded successfully. Something like the code below should work:
<script type="text/javascript">
google.load("jquery");
// Call this function when the page has been loaded
function test_connection() {
if($){
//jQuery WAS loaded.
} else {
//jQuery failed to load. Grab the local copy.
}
}
google.setOnLoadCallback(test_connection);
</script>
The google API documentation can be found here.
A much simpler solution:
<script language="javascript" src="http://maps.google.com/maps/api/js?v=3.2&sensor=false"></script>
and later in the code:
var online;
// check whether this function works (online only)
try {
var x = google.maps.MapTypeId.TERRAIN;
online = true;
} catch (e) {
online = false;
}
console.log(online);
When not online the google script will not be loaded thus resulting in an error where an exception will be thrown.
We are calling jstorage from jquery as in:
$.jstorage.set("foo","bar object");
Later on we look for this key "foo" is gone! Why would this be? We set breakpoints on the jstorage deleteKey method and it is not being called.
Specifically:
$.jstorage.index()
does not contain "foo".
Good lord I found the answer. Let's look at the _save method in jstorage.js, used to persist that set call:
function _save(){
_dropOldEvents(); // remove expired events
try{
_storage_service.jStorage = JSON.stringify(_storage);
// If userData is used as the storage engine, additional
if(_storage_elm) {
_storage_elm.setAttribute("jStorage",_storage_service.jStorage);
_storage_elm.save("jStorage");
}
_storage_size = _storage_service.jStorage?String(_storage_service.jStorage).length:0;
}catch(E7){/* probably cache is full, nothing is saved this way*/}
}
So, let's see, in the jstorage library, where is persists its data, if the local storage is full, and it cannot write, then it simply takes that exception and swallows it. Ugh!
Could I please have my exceptions? In our local copy we at least output this to the console log. But now I know, local storage with its cap of 5 MB on FireFox and 2.5 MB on Chrome, really was too good to be true. I'm a sad panda.
Is it possible to detect if the user is accessing through the browser or application using JavaScript?
I'm developing a hybrid application to several mobile OS through a web page and a PhoneGap application and the goal would be to:
Use the same code independently of the deployment target
Add PhoneGap.js file only when the user agent is an application
You could check if the current URL contains http protocol.
var app = document.URL.indexOf( 'http://' ) === -1 && document.URL.indexOf( 'https://' ) === -1;
if ( app ) {
// PhoneGap application
} else {
// Web page
}
Quick solution comes to mind is,
onDeviceReady
shall help you. As this JS call is invoked only by the Native bridge (objC or Java), the safari mobile browser will fail to detect this. So your on device app(phone gap) source base will initiate from onDeviceReady.
And if any of the Phonegap's JS calls like Device.platform or Device.name is NaN or null then its obviously a mobile web call.
Please check and let me know the results.
I figured out a way to do this and not rely on deviceready events thus, keeping the web codebase intact...
The current problem with using the built in deviceready event, is that when the page is loaded, you have no way of telling the app: "Hey this is NOT running on an mobile device, there's no need to wait for the device to be ready to start".
1.- In the native portion of the code, for example for iOS, in MainViewController.m there's a method viewDidLoad, I am sending a javascript variable that I later check for in the web code, if that variable is around, I will wait to start the code for my page until everything is ready (for example, navigator geolocation)
Under MainViewController.m:
- (void) viewDidLoad
{
[super viewDidLoad];
NSString* jsString = [NSString stringWithFormat:#"isAppNative = true;"];
[self.webView stringByEvaluatingJavaScriptFromString:jsString];
}
2.- index.html the code goes like this:
function onBodyLoad()
{
document.addEventListener("deviceready", onDeviceReady, false);
}
function onDeviceReady(){;
myApp.run();
}
try{
if(isAppNative!=undefined);
}catch(err){
$(document).ready(function(){
myApp.run();
});
}
PhoneGap has window.PhoneGap (or in Cordova, it's window.cordova or window.Cordova) object set. Check whether that object exists and do the magic.
Inside the native call where the url for the phonegap app is loaded you add a parameter target with value phonegap. So the call for android becomes something like this.
super.loadUrl("file:///android_asset/www/index.html?target=phonegap");
Your website using this code won't be called with the extra parameter, so we now have something different between the two deploying platforms.
Inside the javascript we check if the parameter exists and if so we add the script tag for phonegap/cordova.
var urlVars = window.location.href.split('?');
if(urlVars.length > 1 && urlVars[1].search('target=phonegap') != -1){
//phonegap was used for the call
$('head').append('<script src="cordova.js"></script>');
}
A small caveat: this method requires to change the call to index.html in phonegap for each different targeted mobile platform. I am unfamiliar where to do this for most platforms.
what if you try following :
if(window._cordovaNative) {
alert("loading cordova");
requirejs(["...path/to/cordova.js"], function () {
alert("Finished loading cordova");
});
}
I am using the same code for both phonegap app and our web client. Here is the code that I use to detect if phonegap is available:
window.phonegap = false;
$.getScript("cordova-1.7.0.js", function(){
window.phonegap = true;
});
Keep in mind that phonegap js file is loaded asynchronously. You can load it synchronously by setting the correct option of a nifty jquery $.getScript function.
Note that approach does make an extra GET request to grab phonegap js file even in your webclient. In my case, it did not affect the performance of my webclient; so it ended up being a nice/clean way to do this.Well at least until someone else finds a quick one-line solution :)
It sounds like you are loading another webpage once the webview starts in the Phonegap app, is that correct? If that's true then you could add a param to the request url based on configuration.
For example, assuming PHP,
App.Config = {
target: "phonegap"
};
<body onload="onbodyload()">
var onbodyload = function () {
var target = App.Config.target;
document.location = "/home?target=" + target;
};
Then on the server side, include the phonegap js if the target is phonegap.
There is no way to detect the difference using the user agent.
The way I'm doing it with is using a global variable that is overwritten by a browser-only version of cordova.js. In your main html file (usually index.html) I have the following scripts that are order-dependent:
<script>
var __cordovaRunningOnBrowser__ = false
</script>
<script src="cordova.js"></script> <!-- must be included after __cordovaRunningOnBrowser__ is initialized -->
<script src="index.js"></script> <!-- must be included after cordova.js so that __cordovaRunningOnBrowser__ is set correctly -->
And inside cordova.js I have simply:
__cordovaRunningOnBrowser__ = true
When building for a mobile device, the cordova.js will not be used (and instead the platform-specific cordova.js file will be used), so this method has the benefit of being 100% correct regardless of protocols, userAgents, or library variables (which may change). There may be other things I should include in cordova.js, but I don't know what they are yet.
Ive ben struggling with this aswell, and i know this is an old thread, but i havent seen my approach anywhere, so thought id share incase itll help someone.
i set a custom useragent after the actual useragent :
String useragent = settings.getUserAgentString();
settings.setUserAgentString(useragent + ";phonegap");
that just adds the phonegap string so other sites relying on detecting your mobile useragent still works.
Then you can load phonegap like this:
if( /phonegap/i.test(navigator.userAgent) )
{
//you are on a phonegap app, $getScript etc
} else {
alert("not phonegap");
}
To my mind you try to make issue for self. You didn't mentioned your development platform but most of them have different deployment configuration. You can define two configurations. And set variable that indicates in which way code was deployed.
In this case you don't need to care about devices where you deployed your app.
Short and effective:
if (document.location.protocol == 'file:') { //Phonegap is present }
Similar to B T's solution, but simpler:
I have an empty cordova.js in my www folder, which gets overwritten by Cordova when building. Don't forget to include cordova.js before your app script file (it took my one hour to find out that I had them in wrong order...).
You can then check for the Cordova object:
document.addEventListener('DOMContentLoaded', function(){
if (window.Cordova) {
document.addEventListener('DeviceReady', bootstrap);
} else {
bootstrap();
}
});
function bootstrap() {
do_something()
}
New solution:
var isPhoneGapWebView = location.href.match(/^file:/); // returns true for PhoneGap app
Old solution:
Use jQuery, run like this
$(document).ready(function(){
alert(window.innerHeight);
});
Take iPhone as example for your mobile application,
When using PhoneGap or Cordova, you'll get 460px of WebView, but in safari, you'll lose some height because of browser's default header and footer.
If window.innerHeight is equal to 460, you can load phonegap.js, and call onDeviceReady function
Nobody mentioned this yet, but it seems Cordova now supports adding the browser as a platform:
cordova platforms add browser
This will automatically add cordova.js during run-time, which features the onDeviceReady event, so that you do not need to fake it. Also, many plugins have browser support, so no more browser hacks in your code.
To use your app in the browser, you should use cordova run browser. If you want to deploy it, you can do so using the same commands as the other platforms.
EDIT: forgot to mention my source.
Solution: Patch index.html in Cordova and add cordova-platform="android" to <html> tag, so that cordova-platform attribute will be only present in Cordova build and missing from original index.html used for web outside of Cordova.
Pros: Not rely on user agent, url schema or cordova API. Does not need to wait for deviceready event. Can be extended in various ways, for example cordova-platform="browser" may be included or not, in order to distinguish between web app outside of Cordova with Cordova's browser platform build.
Merge with config.xml
<platform name="android">
<hook src="scripts/patch-android-index.js" type="after_prepare" />
</platform>
Add file scripts/patch-android-index.js
module.exports = function(ctx) {
var fs = ctx.requireCordovaModule('fs');
var path = ctx.requireCordovaModule('path');
var platformRoot = path.join(ctx.opts.projectRoot, 'platforms/android');
var indexPath = platformRoot + '/app/src/main/assets/www/index.html';
var indexSource = fs.readFileSync(indexPath, 'utf-8');
indexSource = indexSource.replace('<html', '<html cordova-platform="android"');
fs.writeFileSync(indexPath, indexSource, 'utf-8');
}
Notes: For other than android, the paths platforms/android and /app/src/main/assets/www/index.html should be adjusted.
App can check for cordova-platform with
if (! document.documentElement.getAttribute('cordova-platform')) {
// Not in Cordova
}
or
if (document.documentElement.getAttribute('cordova-platform') === 'android') {
// Cordova, Android
}
I want to know if there is an alternative way to find out if JRE is installed on IE6, besides using the Java deployment toolkit (getJRE()). I tried to use navigator.javaEnabled(), but it returns true no matter if JRE is installed or not. Moreover, navigator.plugins[i].name returns undefined object on IE6.
From an applet:
System.getProperty("java.version");
System.getProperty("java.vendor");
Then you need to get that data from javascript using LiveConnect.
EDIT:
I founded a post with this method in this link
This isnt a nice looking but it works for me on ie6 you could try and catch if error and then even use the var defining the java object as well to check again.
try {
var j = new java.util.Date();
}
catch(err) {
document.write('no java'); // example
}
alert(j) // undefined
there the page RIA Deployment Advice
http://download.oracle.com/javase/6/docs/technotes/guides/jweb/deployment_advice.html
I am trying to browse a website, however, it only works under Windows and Mac because they use the navigator.platform from JavaScript to find out the architecture I am running on. Of course, they also use the browser's user agent, but that was easy to spoof.
Here is the .js in question: http://pastebin.com/f56fd608d. The code responsible for browser detection is at the top. Is there any way of changing the .js file before the site runs, or something similar, so I can eliminate the check?
Using the JavaScript console yields:
>navigator.platform
Linux i686
Evidently I changed the browser's user agent, but navigator.platform does not seem to take it's value from the user agent.
Maybe someone knows how to change the value returned by navigator.platform, because I hate running Windows under VirtualBox to use this site.
EDIT:
This could be of interest because Linux users might be artificially denied access to websites, and can do nothing about it.
var fakePlatformGetter = function () {
return "your fake platform";
};
if (Object.defineProperty) {
Object.defineProperty(navigator, "platform", {
get: fakePlatformGetter
});
Object.defineProperty(Navigator.prototype, "platform", {
get: fakePlatformGetter
});
} else if (Object.prototype.__defineGetter__) {
navigator.__defineGetter__("platform", fakePlatformGetter);
Navigator.prototype.__defineGetter__("platform", fakePlatformGetter);
}
Since you can't directly set navigator.platform, you will have to be sneaky - create an object that behaves like navigator, replace its platform, then set navigator to it.
var fake_navigator = {};
for (var i in navigator) {
fake_navigator[i] = navigator[i];
}
fake_navigator.platform = 'MyOS';
navigator = fake_navigator;
If you execute this code before the document loads (using GreaseMonkey, an addon or a Chrome extension), then the page will see navigator.platform as "MyOS".
Note: tested only in Chrome.
Provided that the browser you're using supports Object.defineProperty() (it likely does), a more modern way of achieving the same goal is as follows:
Object.defineProperty(navigator, 'platform', {
value: 'my custom value',
configurable: true // necessary to change value more than once
});
This allows you to set it to any custom value you want, and it also allows you to change it as many times as you want without needing to reload the page.
For a Mozilla-based browser, GreaseSpot / Code Snippets # Hijacking browser properties demonstrates how it may be done. This code may be injected from a GreaseMonkey script.
about:config - > general.platform.override
Attempting to change this property (at any time) in Firefox yields:
Error: setting a property that has only a getter
Source File: index.html
Line: 1
So I think you will have a hard time.
I'd try to contact the author about obtaining a fix.