I am using Firefox 21. I wrote the code below to display the contents of an indexedDB object store on page load.
window.indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB ||
window.msIndexedDB;
window.IDBTransaction = window.IDBTransaction || window.webkitIDBTransaction ||
window.msIDBTransaction;
window.IDBKeyRange = window.IDBKeyRange || window.webkitIDBKeyRange ||
window.msIDBKeyRange;
var request = window.indexedDB.open('mgDB', 1);
request.onerror = function(e) {
alert('error');
};
request.onupgradeneeded = function(e) {
alert('upgradeneeded');
};
request.onsuccess = function(e) {
alert('success');
};
Knowing that mgDB does not exist yet, I expected the upgradeneeded event to fire. When I debugged the code using Firebug, I see error, onsuccess and onupgradeneeded having null values, so none of the events fired. When I execute the code without debug mode, I see the success event being fired. Does anyone know why that happens?
The fact that the onupgradeneeded doesn't fire is because you ran the code already several time and the database with version one is made the first time. The logic of the open function is, create the db if it doesn't exist, upgrade if the version of the database is lower than the provided version. (Keep in mind the indexeddb is persistent storage, meaning it isn't destroyed if you close the browser) If you want to be sure you want to enter the onupgradeneeded every time (for testing pupouses!!!) you can delete the database before opening/creating it again.
The fact that the events are null is maybe the depending on the place you put your breakpoint? Put a breakpoint in one of the callbacks, and you will see the onsuccess, onerror, ... will be filled up on the request object.
Related
I am experimenting with the new way of handling page events in jqM and have run into a curious issue. When handling the pagecontainerbeforechange event
$(document).on('pagecontainerbeforechange',function(e,u){test(e,u,'changing');})
function test(e,u,msg){console.log($(u.toPage));}
Attempting to put a jQuery object wrapper around u.toPage - as done above - produces strange behavior.
Check out this fiddle to see what I mean
Click on the Second Page button and then view the console. Nothing will happen (the second page is not shown) and you will see a message along the lines of *Uncaught error:syntax error, unrecognized expression http://jsfiddle.net/egn7g5xb/1/show/#second
Now comment out Line 7 and run the fiddle again. No such issue this time and the second page gets shown.
Perhaps someone here might be able to explain what is going on here?
On initial run, jQuery Mobile creates a fake page before navigating to first page in DOM. At that stage, pagecontainerbeforechange fires twice and returns .toPage as an object.
Later on, upon navigating to other pages, it fires twice again; however, it returns a string first time (URL/hash) and second time it returns an object which is the page itself.
Therefore, when using that event, you have to determine whether .toPage is an object or a string.
$(document).on("pagecontainerbeforechange", function (e, data) {
if (typeof data.toPage == "string") {
/* parse url */
}
if (typeof data.toPage == "object") {
/* manipulate page navigating to */
}
});
Note that pagecontainerbeforetransition is similar to beforechange, however, it fires once and returns .toPage as an object.
First, create your pagecontainer events within $(document).on("pagecreate", "#first", function(){ .. }).
Then the selector for these events should be $(":mobile-pagecontainer") or $("body") NOT $(document).
function test(e,u,msg)
{
console.log(msg);
var IsJQ = u.toPage instanceof $;
console.log(IsJQ);
if (IsJQ){
console.log(u.toPage.data());
} else {
console.log(u.toPage);
}
console.log('---');
}
$(document).on("pagecreate", "#first", function(){
$(":mobile-pagecontainer").on('pagecontainerbeforechange', function (e, u) {
test(e,u,'changing');
});
$(":mobile-pagecontainer").on('pagecontainerchange',function(e,u){
test(e,u,'changed');
});
});
Updated FIDDLE
I admit I'm quite noob with full ajax websites, and so I'm surely making some mistakes.
The problem is this:
in http://lamovida.arabianessence.com
every page is loaded with an $.ajax call using this function
function getAjaxPage() {
$('a.ajaxc').click(function() {
$("li.page_block").find(".wrapper").fadeOut(400).remove();
hideSplash();
var $thishref = $(this).attr('href'),
$thisurl = $thishref.replace("#!/",""),
$urlArr = $thisurl.split('-'),
$urlOk = $urlArr[0],
$dataOk = $urlArr[1];
$.ajax({
url : $urlOk + ".php",
data : 'id='+$dataOk,
success : function (data,stato) {
$("#content").css({opacity:1}).fadeIn(400);
$("li.page_block").html(data);
$("li.page_block").css('visibility', 'visible');
$("li.page_block").find(".wrapper").css({opacity:0}).show().animate({opacity:1},1000);
var $whgt = $(".wrapper").height(),
$ctop = ( ( $(window).height() - $whgt ) /2 )-40;
$("#content").stop().animate({height: $whgt+40, top: $ctop},1000);
$("li.page_block").css('padding-top',20);
$('.scrollable').jScrollPane();
$('.slider>ul>li').jScrollPane();
getAjaxPage();
},
error : function (richiesta,stato,errori) {
alert(errori);
}
});
});
}
Every time this function is called the content gets loader slower, and after about 20 clicks things get real bad, and the loading time grows and grows.
I tried to analyze the situation using the Google Chrome's Timeline, and I saw that after each click the browser uses more memory. If I comment the getAjaxPage(); row in the "success" section the situation starts to get better, but of course I lose all the internal navigation.
What could I do to avoid this problem?
Many thanks to all!
Every call to $('a.ajaxc').click() is adding new event handler thus every click causes more requests to be made. After the first click, every click will cause two requests. Another click? Another three requests. Etc.
Put the handler outside the function and you will have only one AJAX call per click:
$(document).ready(function() {
$('a.ajaxc').click(getAjaxPage);
});
I also don't see the reason behind calling getAjaxPage again from within the callback, so remove it as well to avoid infinite loop of requests.
I am trying to scrape information from a specified website. This site uses authentication first, thus a i use zombie.js:
var Browser = require("zombie");
var browser = new Browser();
browser.visit("https://*****login.aspx", function(){
browser.fill('#user', '*****');
browser.fill('#pwd', '*****');
var button = browser.querySelector('#btnSubmit');
browser.fire('click', button, function(){
//scraping main.aspx
});
});
It's working, i can scrape the main.aspx: there is a <table>, containig information about new messages(from, date, subject,), the problems comes here: the subject field is clickable, and clicking on it makes a new window appear with the actual message. However it is an ajaxgrid, and when i perform a click:
var field = browser.querySelector('#VeryLongIdOfTheField');
browser.fire('click', field, function(){
console.log(browser.querySelector('#VeryLongIdOfTheFieldContainingTheMessage').innerHTML);
});
it returns an error message, saying that undefined has no innerHTML. I suppose its because this action handled with some ajax magic. I am new in this js/nodejs/jquery/.. world, some help needed to enlight me.
Since the data is populated using async ajax, I'm guessing there's a lag between your click and the actual DOM population inside the node. How about waiting for a bit before checking the content inside the node.
browser.fire('click', field, function(){
setTimeout(function(){
console.log(browser.querySelector('#VeryLongIdOfTheFieldContainingTheMessage').innerHTML);
}, 3000)
});
If the time taken is not very predictable, you could also run it inside a loop until you find the content or exit after a reasonable number of retries.
On my website I have mouse over and mouse out events set up on an HTML table. These events trigger ajax requests, and perform certain actions etc. However, i want to be able to not trigger a second request if one is already running. So, is there away to detect these requests, and therefore avoid a second. Incidentally Im using the jQuery $.ajax()
if it helps at all.
Thanks in advance
Chris
I'd try something simple like:
var requestMade = false;
function yourAjaxFunction(){
if(!requestMade)
{
requestmade = true;
$.ajax({
url: "page",
success: function(){
requestMade = false;
}
error: function(){
requestMade = false;
}
});
}
}
You can use the success: and error: settings to change the variable back to false.
I have never used the error so you may have to include some other things in it, but this is the general idea.
For this suppose I'd use ajaxStart() and ajaxStop() which would change specific variable ajaxRunning which could be checked before sending the request (maybe in ajaxStart() directly?)
Set global or local static variable to true when first ajax is about to trigger, than add if before triggering the second one ;) Than after one request is finished, set this variable to false
I'm running into an issue with an async call to the server that only works one time, then it appears to become a synchronous call. Let me try to explain.
It's an MVC 2.0 site, using ASP.NET and Ajax. I'm using the Ajax.BeginForm helper, like so:
<% using (Ajax.BeginForm("Start", null,
new { virtualMachineId = xyz },
new AjaxOptions { UpdateTargetId = "VirtualMachineForm", OnBegin="OnStartingVm" }
)){
Then while the machine is starting I want to call back to the server and get an update every second. It works the first time correctly, then changes behavior. OnStartingVm looks something like this:
function OnStartingVm() {
$('#StartingDiv').css('visibility', 'visible');
$('#StartingDiv').show();
var vmId = xyz;
intervalId = setInterval(function () {
updateStartingStatus(vmId)
}, 1000);
}
function updateStartingStatus(vmId) {
/* This part always runs */
$.ajax({
url: "/member/vm/getstartingstatus/" + vmId,
dataType: 'json',
async: true,
success: function (data) {
alert('This part runs every second on the first time only');
if (data.status == "Running") {
$('#StartingDiv').text(data.percentComplete);
}
else {
$('#StartingDiv').css('visibility', 'hidden');
$('#StartingDiv').hide();
clearInterval(intervalId);
}
},
});
}
Within the updateStartingStatus function, the first part runs every second, every time. However, within the Ajax call, the success result works every second on the first time only. Then on the second time I click on the start button all of the requests queue up. After the starting has completed, about 20 seconds later, I get a bunch of alert windows back to back. So, I can tell that updateStartingStatus runs every second every time, but the ajax call appears to switch to become a sync call after the first time.
Refreshing the browser window doesn't help. I have to fully close it and open it again. The same occurs in IE and Chrome.
One more thing to note is that the updated div (VirtualMachineForm) contains most of the page, including the button being pressed. So it basically replaces the page from under itself. Not sure if that would cause any issues.
Additionally, if I debug in Visual Studio 2010, the call isn't made to the controller action when the issue occurs. So, it appears to be something client-side. I've ruled out any issues server-side.
I eventually figured it out. This post lead to the answer.
It was session state related and the browser locked the request until a previous one was completed. I didn't need to disable session state, but I had to avoid a session write from code.
That explains why a browser refresh didn't work and why I had to close and open the browser again.
Why don't you call clearInterval function?