Navigating in a WinJS app always throws an exception - javascript

Every time I try to perform a navigation in the ready function of a page, the application crashes.
Specifically, it fails at the WinJS.Navigation.navigate("/pages/login/login.html", {}); line below:
// This function is called whenever a user navigates to this page. It
// populates the page elements with the app's data.
ready: function (element, options) {
var listView = element.querySelector(".groupeditemslist").winControl;
listView.groupHeaderTemplate = element.querySelector(".headertemplate");
listView.itemTemplate = element.querySelector(".itemtemplate");
listView.oniteminvoked = this._itemInvoked.bind(this);
// Set up a keyboard shortcut (ctrl + alt + g) to navigate to the
// current group when not in snapped mode.
listView.addEventListener("keydown", function (e) {
if (appView.value !== appViewState.snapped && e.ctrlKey && e.keyCode === WinJS.Utilities.Key.g && e.altKey) {
var data = listView.itemDataSource.list.getAt(listView.currentItem.index);
this.navigateToGroup(data.group.key);
e.preventDefault();
e.stopImmediatePropagation();
}
}.bind(this), true);
this._initializeLayout(listView, appView.value);
listView.element.focus();
initialize();
}
function initialize() {
// Check if user is logged in
if (is_logged_in !== true) {
WinJS.Navigation.navigate("/pages/login/login.html", {});
}
else {
// TODO: Replace the data with your real data.
// You can add data from asynchronous sources whenever it becomes available.
generateSampleData().forEach(function (item) {
list.push(item);
});
}
}
Anyone know why this happens?

There are a couple routes you could take here:
Catch the unhandled exception and ignore it
Structure your code to avoid setting up the error condition
To ignore the error you can setup a WinJS.Application.onerror handler that can deal with unhandled exceptions. Here's a forum post that guides you in this solution: http://social.msdn.microsoft.com/Forums/en-US/winappswithhtml5/thread/686188b3-852d-45d5-a376-13115dbc889d
In general, I'd say you're better off avoiding the exception all together. To that end - What's happening here is that only one navigation event (promise) can occur at a time. The navigation promise used to navigate to groupedItems is still running when you're inside of the ready function. When you call initialize, which then calls WinJS.Navigation.navigate("/pages/login/login.html", {}); it sees this and tries to first cancel the currently running navigation promise which results in the exception you're seeing.
Instead, you can use the window.setImmediate function to setup your call to initialize() to run after the current script block exits. To do this, replace your call to initialize() with:
window.setImmediate(this.initialize.bind(this));

If your running your code on the RTM version after coming from the Release Preview this should sort your problem.
function initialize() {
// Check if user is logged in
if (is_logged_in !== true) {
WinJS.Navigation.navigate("/pages/login/login.html", {});
}
else {
// TODO: Replace the data with your real data.
// You can add data from asynchronous sources whenever it becomes available.
generateSampleData().forEach(function (item) {
list.push(item);
});
}
}
var markSupportedForProcessing = WinJS.Utilities.markSupportedForProcessing;
var requireSupportedForProcessing = WinJS.Utilities.requireSupportedForProcessing;
markSupportedForProcessing(initialize);
requireSupportedForProcessing(initialize);
You should probably take a look at the migration docs which details what the above is actually for and why: http://www.microsoft.com/en-us/download/details.aspx?id=30706

Related

How to make this run only once?

I'm trying to get it where If someone clicks the button it will update the database but what happens if I enter 50 then it will keep running it and I have a tracking board that sums everything up so it overloads my server and makes the total in the 1000's when its normally just over 100.
I've tried a document ready function, I've had on and one. ('click') and it keeps running multiple times
$('#update_new_used-counter').one('click', function (event) {
event.preventDefault();
let updated_new_counter = $('#new_sold-update').val().trim();
let updated_used_counter = $('#used_sold-update').val().trim();
trackingBoardRef.on("value", function(snapshot) {
let current_new_counter = snapshot.val().new;
let current_used_counter = snapshot.val().used;
if (updated_new_counter == '') {
trackingBoardRef.update({
new: current_new_counter,
});
} else {
trackingBoardRef.update({
new: updated_new_counter,
})
};
if (updated_used_counter == '') {
trackingBoardRef.update({
used: current_used_counter,
});
} else {
trackingBoardRef.update({
used: updated_used_counter,
})
};
console.log(snapshot.val().new);
console.log(snapshot.val().used);
});
});
That's what I have now and it just keeps running multiple times until firebase says I had to many requests and stops it. I just want it to update once
When you call:
trackingBoardRef.on("value", function(snapshot) {
You attach a listener to the data in trackingBoardRef that will be triggered right away with the current value, and then subsequently whenever the data under trackingBoardRef changes. And since you're changing data under trackingBoardRef in your code, you're creating an infinite loop.
If you only want to read the data once, you can use the aptly named once method:
trackingBoardRef.once("value", function(snapshot) {
...
Note that if you're update the value under trackingBoardRef based on its current value, you really should use a transaction to prevent users overwriting each other's changes.

What should I do with the redundant state of a ServiceWorker?

I gotta a companion script for a serviceworker and I'm trialling right now.
The script works like so:
((n, d) => {
if (!(n.serviceWorker && (typeof Cache !== 'undefined' && Cache.prototype.addAll))) return;
n.serviceWorker.register('/serviceworker.js', { scope: './book/' })
.then(function(reg) {
if (!n.serviceWorker.controller) return;
reg.onupdatefound = () => {
let installingWorker = reg.installing;
installingWorker.onstatechange = () => {
switch (installingWorker.state) {
case 'installed':
if (navigator.serviceWorker.controller) {
updateReady(reg.waiting);
} else {
// This is the initial serviceworker…
console.log('May be skipwaiting here?');
}
break;
case 'waiting':
updateReady(reg.waiting);
break;
case 'redundant':
// Something went wrong?
console.log('[Companion] new SW could not install…')
break;
}
};
};
}).catch((err) => {
//console.log('[Companion] Something went wrong…', err);
});
function updateReady(worker) {
d.getElementById('swNotifier').classList.remove('hidden');
λ('refreshServiceWorkerButton').on('click', function(event) {
event.preventDefault();
worker.postMessage({ 'refreshServiceWorker': true } );
});
λ('cancelRefresh').on('click', function(event) {
event.preventDefault();
d.getElementById('swNotifier').classList.add('hidden');
});
}
function λ(selector) {
let self = {};
self.selector = selector;
self.element = d.getElementById(self.selector);
self.on = function(type, callback) {
self.element['on' + type] = callback;
};
return self;
}
let refreshing;
n.serviceWorker.addEventListener('controllerchange', function() {
if (refreshing) return;
window.location.reload();
refreshing = true;
});
})(navigator, document);
I'm a bit overwhelmed right now by the enormity of the service workers api and unable to "see" what one would do with reg.installing returning a redundant state?
Apologies if this seems like a dumb question but I'm new to serviceworkers.
It's kinda difficult to work out what your intent is here so I'll try and answer the question generally.
A service worker will become redundant if it fails to install or if it's superseded by a newer service worker.
What you do when this happens is up to you. What do you want to do in these cases?
Based on the definition here https://www.w3.org/TR/service-workers/#service-worker-state-attribute I am guessing just print a log in case it comes up in debugging otherwise do nothing.
You should remove any UI prompts you created that ask the user to do something in order to activate the latest service worker. And be patient a little longer.
You have 3 service workers, as you can see on the registration:
active: the one that is running
waiting: the one that was downloaded, and is ready to become active
installing: the one that we just found, being downloaded, after which it becomes waiting
When a service worker reaches #2, you may display a prompt to the user about the new version of the app being just a click away. Let's say they don't act on it.
Then you publish a new version. Your app detects the new version, and starts to download it. At this point, you have 3 service workers. The one at #2 changes to redundant. The one at #3 is not ready yet. You should remove that prompt.
Once #3 is downloaded, it takes the place of #2, and you can show that prompt again.
Write catch function to see the error. It could be SSL issue.
/* In main.js */
if ('serviceWorker' in navigator) {
navigator.serviceWorker.register('./sw.js')
.then(function(registration) {
console.log("Service Worker Registered", registration);
})
.catch(function(err) {
console.log("Service Worker Failed to Register", err);
})
}

How to add observer for nsIBrowserSearchService

I'm having trouble adding an observer to watch for changes in firefox's search engines. I read the nsIBrowserSearchService page on the Mozilla Developer Site which suggests to use the init() method of the Services.search object.
void init([optional] in nsIBrowserSearchInitObserver observer);
I tried that and I managed to get it to execute the function once on start up but it never calls it again when I add or remove or reorder the search engines. So I'm doing something wrong.
I have experience with observers but only with using general preferences and I generally use add them and remove them using the code below. I'm not sure how to do it with the nsIBrowserSearchService . I would like to observe the nsIBrowserSearchService in the same or a similar way but I'm not sure what I would put for
branch = Services.prefs.getBranch("preferenceNameHere");
I'm not observing Services.prefs but Services.search I assume, and that has no getBranch method as far as I can tell.
This is how I normally add and remove the observer in Chrome.js
const {Ci, Cu} = require("chrome");
const {Services} = Cu.import("resource://gre/modules/Services.jsm", {});
branch = Services.prefs.getBranch("preferenceNameHere");
branch.addObserver("", observe, false);
function observe(subject, topic, data) {
// instanceof actually also "casts" subject
if (!(subject instanceof Ci.nsIPrefBranch)) {
return;
}
//do stuff here
};
exports.onUnload = function(reason) {
// Need to remove our observer again! This isn't automatic and will leak
// otherwise.
branch.removeObserver("", observe);
if(reason == "disable" || reason == "uninstall"){
//restore changes made by addon
}
};
Can anyone advise me on how to do this so I can observe for changes and ensure that I remove the observer properly with the search object. Thanks
What you are trying above is trying to use pref observer on non-prefs, this is not possible. You have to use the regular observer service like this.
This notifies you when the user changes the engine.
Cu.import('resource://gre/modules/Services.jsm');
var observers = {
'browser-search-engine-modified': {
aTopic: 'browser-search-engine-modified',
observe: function (aSubject, aTopic, aData) {
if (aData == 'engine-current') {
console.log('current engine was changed!');
//console.log('aSubject on change:', aSubject.name, 'same as Services.search.currentEngine.name:', Services.search.currentEngine.name); //aSubject is the engine
//console.log('aTopic on change:', aTopic); //aTopic is obviously `browser-search-engine-modified`
}
},
reg: function () {
Services.obs.addObserver(observers[this.aTopic], this.aTopic, false);
},
unreg: function () {
Services.obs.removeObserver(observers[this.aTopic], this.aTopic);
}
}
};
To start listening do this:
for (var o in observers) {
observers[o].reg();
}
To stop listening do this:
for (var o in observers) {
observers[o].unreg();
}
I'm not sure what happens when user adds a new engine but doenst select it. Or if he removes a engine. Please let me know what those messages are when user does that.

Focus issues make tests failing

I'm using osx 10.9.2, protractor 0.21.0, selenium-server-standalone 2.40.0 and chromedriver 2.9.
I'm having some problems, which (I believe) was due to window focusing issue.
When I run my e2e test using protractor, the browser window would show but my terminal will still be the one in focus. This is apparent from "Terminal" was still shown in my menu bar rather than "Chrome" (osx behavior that indicates which app is in focus).
I tried to remedy the situation by doing this to no avail:
browser.driver.getAllWindowHandles().then(function(handles) {
console.log(handles[0]);
browser.driver.switchTo().window(handles[0]);
});
This situation causes some of my tests to fail. For example, tests that include clicking a field with bootstrap datepicker won't show the calendar and making my test cannot interact with the datepicker calendar.
The situation is even worse on firefox. Firefox won't even show any dropdown menu when clicked if the browser is not in focus.
Funnily, when I click the browser window manually after it shows up the first time, the tests will work normally.
When I tried a different approach: Doing the test on a freshly installed debian linux, still not working. Behavior is similar as described above.
These are my configuration files: https://gist.github.com/giosakti/ca24a13705d15f4374b0
Unfortunately IE & Firefox don't ensure the windows handlers order, so we need iterate them. And getting focus on the new browser window/tab can be tricky too.
I've run into these issues so i created:
A helper function to overcome those issues
// Needs an element to make sure we are on the correct popup
var waitForPopUpHandle = function(elm, errorMessage) {
if (errorMessage == null) {
errorMessage = 'Expected a new browser tab or window to pop up';
};
if (elm == null) {
throw 'waitForPopUpHandle needs an element to wait for!';
};
browser.ignoreSynchronization = true; // not a protractor page
// IE & Firefox don't ensure the windows handlers order, so we need iterate them.
// First wait to have more that 1 browser tab
browser.manage().timeouts().implicitlyWait(300); // a reasonable wait-retry time
var i = 0;
var popUpHandle = browser.driver.wait(function() {
return browser.getAllWindowHandles().then(function(handles) {
if (handles.length > 1) {
return browser.switchTo().window(handles[i]).then(function() {
return browser.driver.isElementPresent(elm).then(function(result) {
if (result) {
return handles[i];
} else {
browser.sleep(400); // give it a break
i = i + 1;
if (i >= handles.length) {
i = 0;
};
return false;
};
});
});
} else {
browser.sleep(400); // give it a break
return false;
};
});
}, browser.params.timeouts.pageLoadTimeout, errorMessage);
// restore implicit wait
browser.manage().timeouts().implicitlyWait(0); //restore
return popUpHandle;
};
Sample usage of that helper
var popUpHandle = waitForPopUpHandle(by.css('div.some-element-unique-to-that-popup'));
browser.switchTo().window(popUpHandle).then(function() {
browser.ignoreSynchronization = true; // not an angular page
browser.driver.findElement(by.css('div.some-element-unique-to-that-popup')); // wait for the elm
// your expect()'s go here ...
// ...
browser.close().then(function() {
// This close() promise is necessary on IE and probably on Firefox too
var mainTab = waitForMainWindow();
expect(browser.switchTo().window(mainTab).then(function() {
browser.ignoreSynchronization = false; // restore if main window is an angular page
// Ensure we are back on the main window
// ....
return true;
})).toBe(true);
});
});
And finally waitForMainWindow helper
var waitForMainWindow = function(errorMessage) {
if (errorMessage == null) {
errorMessage = 'Expected main browser window to be available';
};
browser.ignoreSynchronization = true; // not an angular page
return browser.driver.wait(function() {
return browser.getAllWindowHandles().then(function(handles) {
if (handles.length > 1) {
var hnd = handles[handles.length - 1];
return browser.switchTo().window(hnd).then(function() {
return browser.close().then(function() {
browser.sleep(400); // wait for close
return false;
});
});
} else {
return handles[0];
};
});
}, 5000, errorMessage);
};
I found a silver lining! I downgrade the chrome using installer from http://google-chrome.en.uptodown.com/mac/old and the focus issues are gone.. (the issues still persist on firefox though)..
If you search "chrome 34 focus issues" on google, you will find several reports that maybe correlate with this issue. for example: https://productforums.google.com/forum/#!topic/chrome/pN5pYf2kolc
but I still don't know whether this was a bug or expected behavior of chrome 34. So for now I block google updater and use Chrome 33.

Javascript Variable Sometimes Undefined

I know this question has been asked several times, but I couldn't seem to find a solution that worked for me in any of the previous questions. I have a variable that gets set when my HTML page is done loading, but sometimes when my code tries to access that variable, it says that it is undefined. I'm not sure why, since I believe I am waiting for everything to load properly. This exception seems to happen randomly, as most of the time all the code runs fine. Here's a simplified version of my code:
var globalVar;
function initStuff(filePath) {
// I wait till the HTML page is fully loaded before doing anything
$(document).ready(function(){
var video = document.getElementById("videoElementID");
// My parseFile() function seems to run smoothly
var arrayOfStuff = parseFile(filePath);
if (arrayOfStuff == null) {
console.error("Unable to properly parse the file.");
} else {
setGlobalVariable(arrayOfStuff);
video.addEventListener("play", updateVideoFrame, false);
}
});
}
function setGlobalVariable(arrayOfStuff) {
window.globalVar = arrayOfStuff;
}
function updateVideoFrame() {
// A bunch of other code happens first
// This is the line that fails occasionally, saying
// "window.globalVar[0].aProperty.anArray[0] is undefined"
var test = window.globalVar[0].aProperty.anArray[0].aProperty;
}
The only thing that I can think of that might be causing this problem is some sort of synchronicity issue. I don't see why that would be the case, though. Help please!
Edit:
In case the asynchronicity issue is coming from my parseFile(xmlFile) method, here is what I'm doing there. I thought it couldn't possibly be causing the issue, since I force the method to happen synchronously, but in case I'm wrong, here it is:
function parseKML(xmlFile) {
var arrayOfStuff = new Array();
// Turn the AJAX asynchronicity off for the following GET command
$.ajaxSetup( { async : false } );
// Open the XML file
$.get(xmlFile, {}, function(xml) {
var doc = $("Document", xml);
// Code for parsing the XML file is here
// arrayOfStuff() gets populated here
});
// Once I'm done processing the XML file, I turn asynchronicity back on, since that is AJAX's default state
$.ajaxSetup( { async : true } );
return arrayOfStuff;
}
The first thing you should do in your code is figure out which part of:
window.globalVar[0].aProperty.anArray[0]
is undefined.
Since you have multiple chained property references and array references, it could be many different places in the chain. I'd suggest either set a breakpoint right before your reference it examine what's in it or use several console.log() statement sto output each nested piece of the structure in order to find out where your problem is.
console.log("globalVar = " + globalVar);
console.log("globalVar[0] = " + globalVar[0]);
console.log("globalVar[0].aProperty = " + globalVar[0].aProperty);
console.log("globalVar[0].aProperty.anArray = " + globalVar[0].aProperty.anArray);
console.log("globalVar[0].aProperty.anArray[0] = " + globalVar[0].aProperty.anArray[0]);
If the problem is that globalVar isn't yet set, then you have a timing problem or an initialization problem.
If the problem is that one of the other properties isn't set, then you aren't initializing globalVar with what you think you are.
You may also want to write your code more defensibly so it fails gracefully if some of your data isn't set properly.
You need to use defensive programming.
http://www.javascriptref.com/pdf/ch23_ed2.pdf
Example:
var video = document.getElementById("videoElementID") || 0;
-
if( video && video.addEventListener ){
video.addEventListener("play", updateVideoFrame, false);
}
Here's another version of your code.
window.globalVar = globalVar || [];
function setGlobalVariable(arrayOfStuff) {
window.globalVar = arrayOfStuff;
}
function updateVideoFrame() {
// A bunch of other code happens first
// This is the line that fails occasionally, saying
// "window.globalVar[0].aProperty.anArray[0] is undefined"
if( window.globalVar ){
var g = window.globalVar || [];
var d = (g[0] || {})["aProperty"];
// etc...
}else{
console.error( "test error." );
}
}
function initStuff(filePath) {
// I wait till the HTML page is fully loaded before doing anything
$(document).ready(function () {
var video = $("#videoElementID");
// My parseFile() function seems to run smoothly
var arrayOfStuff = parseFile(filePath) || [];
if (arrayOfStuff == null || video == null ) {
console.error("Unable to properly parse the file.");
} else {
setGlobalVariable(arrayOfStuff);
video.bind("play", updateVideoFrame);
}
});
}

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