I need to detect the first time a page loads in jQuery so that I can perform some actions only when the page loads the first time a user navigates to that page. Similar to server side code page.ispostbasck. I have tested $(document).ready and it fires every time the page loads so this will not provide what I need. I have also tried the jQuery Load function - it also fires every page load. So by page load an example is that I have an HTML input tag on the page of type button and it does not fire a postback (like an asp.net button) but it does reload the page and fires $(document).ready
Thanks
You will have to use cookie to store first load information:
if (! $.cookie("cookieName")){
// do your stuff
// set cookie now
$.cookie("cookieName", "firstSet", {"expires" : 7})
}
Note: Above example uses jQuery Cookie plugin.
An event doesn't exist that fires only when the page is loaded for the first time.
You should use jQuery's .ready() event, and then persist the fact that you've handled a first time page load using your method of choice (i.e. cookie, session variable, local storage, etc.).
Note: This method will never be fool proof unless you can store this information at the user level in a DB. Otherwise, as soon as the user clears their cookies, or whatever method you choose, the "first time loaded" code will fire again.
I just ran into this problem and this is how I handled it. Keep track of the first time the page loads by using a variable initialLoad:
var initialLoad = true;
$(document).ready(function() {
...
...
...
initialLoad = false;
});
Then in other functions, you can do this:
if (initialLoad) {
//Do work that is done when the page was first refreshed/loaded.
} else {
//Do work when it's not the initial load.
}
This works well for me. If the user is already on the page and some jQuery functions run, I now know if that user just loaded the page or if they were already on the page.
The easy solution is to use jQuery ‘Once’ plugin
$(element).once('class-name', function() {
// your javascript code
});
Related
I'm building a JQuery mobile site which has an image slider on 2 pages. The sliders are activated using the following JS:
$(function () {
$("#slider").excoloSlider();
});
where '#slider' is the name of the div that gets rendered as the slider.
I have this slider on the 2 pages and have given both the same id, and don't want to insert the above code into both pages. To make things easy I want to be able to make add the above code into a.js file that I'm referencing at the top of both pages.
However, the script only kicks in when one of the pages are the first page to be navigated to. So, I assume this means the code is only being called in the once, and due to the AJAX loading of the subsequent page, it isnt called when this new page loads.
So, how can I run the code to affect any/all pages which feature the slider?
I dont know how many times you have to call .excoloSlider(); function. In case you have to call it each time the page is visited, then you need to use any of these page events, pagecontainershow or pagecontainerbeforeshow.
If you use pagecontainershow, you can run .excoloSlider(); on #slider even if you have the same id in a different page. This way, you specify in which page to look for #slider.
$(document).on("pagecontainershow", function () {
var activePage = $.mobile.pageContainer.pagecontainer("getActivePage");
/* check if #slider is within active page */
var slider = activePage.find("#slider").not(".slider");
if(slider) {
slider.excoloSlider();
}
});
Update
I have added .not(".slider") selector to exclude already rendered slider. The function .excoloSlider() will be called on new sliders only.
Demo
Try to use class instead of id since id is unique, then you can change your jQuery code to:
$(function () {
$(".slider").excoloSlider();
});
Use jQuery Mobile API for the navigation system
$(window).on( "navigate", function( event, data ) {
$("#slider").excoloSlider();
});
Edit
Use pageinit
From the jQM docs:
Important: Use $(document).bind('pageinit'), not $(document).ready()
The first thing you learn in jQuery is to call code inside the
$(document).ready() function so everything will execute as soon as the
DOM is loaded. However, in jQuery Mobile, Ajax is used to load the
contents of each page into the DOM as you navigate, and the DOM ready
handler only executes for the first page. To execute code whenever a
new page is loaded and created, you can bind to the pageinit event.
This event is explained in detail at the bottom of this page.
I wonder if i've unset($_SESSION['enough']); and want to free it up on closing the page.
[ suppose visitor is viewing page of the website pages in new tab ]
i'm using this code
<script language="javascript">
window.onbeforeunload = function() {
console.log('event');
return false;
}
</script>
i wonder how can i apply to fire this code unset($_SESSION['login_id']); , it might look ridicules but this is the basic idea and i'm gonna give example what can be used for
For example : media website would like members not to watching more than one video in same time so the watching page drop session and free it on closing it so can watch more! js indeed is essential for website using jwplayer so no chance of talking about members with disabled js.
In order to load the killsession.php that runs the unset() command, you can run that page with ajax with async:false
Have a look at
Ajax request with JQuery on page unload
jQuery.ajax({url:"http://localhost/killsession.php", async:false})
You can use jQuery to fire on unload with the unload function (http://api.jquery.com/unload/).
$( window ).unload(function() {
// On the unload, we can fire a request back to the server
// .get(), .post(), and .ajax() may be useful.
});
I am writing a webapp using jQuery Mobile that calls a function to load records into localStorage and create a listview from a remote JSON file when the page is initially created (using the live.pagecreate() event for the page). At the beginning of this function is the jQuery Mobile method $.mobile.showPageLoadingMsg() and $.mobile.hidePageLoadingMsg() is at the end of the function.
On the initial pagecreate, the loading message does not appear (on iPhone 4 with iOS 4.3 Safari, Chrome 13 and Firefox 5). However, I also have a refresh button on the page; this button clears the associated records in localStorage then calls the same function used to initially populate the listview. However, when calling the same function from the refresh button the showPageLoadingMsg() and hidePageLoadingMsg() both work correctly and the Loading screen appears and disappears as it should. Am I missing something here?
ETA Here is the gist of the code (not in front of the actual code right now, if you need more I will put it in tonight). I also should mention that I've tried to put showPageLoadingMsg in (document).ready and have tried to bind it to mobileinit and neither have worked:
function loadListView(){
$.mobile.showPageLoadingMsg();
//ajax call to pull JSON
//$.each loop to load localStorage and listview
$.listview.refresh('list');
$.mobile.hidePageLoadingMsg();
}
$(#listpage).live('pagecreate', function(event){
loadListView(); // showPageLoadingMsg() and hidePageLoadingMsg do not work when the function is called here
});
function clearList(){
//for loop that clears each item in localStorage that matches the key prefix set in loadListView
}
//runs when refresh button is clicked
$('listrefresh').live('click',function(){
clearList();
loadListView(); //showPageLoadingMsg() and hidePageLoadingMsg() work when the function is called here
});
For these handlers to be invoked during the initial page
load, you must bind them before jQuery Mobile executes. This can be
done in the mobileinit handler, as described on the global config
page.
Docs:
http://jquerymobile.com/demos/1.0b2/#/demos/1.0b2/docs/api/events.html
Triggered on the page being initialized, after initialization occurs.
We recommend binding to this event instead of DOM ready() because this
will work regardless of whether the page is loaded directly or if the
content is pulled into another page as part of the Ajax navigation
system.
Example:
http://jsfiddle.net/phillpafford/mKn8Y/8/
In the example none of the live events fire on initial page load, you have to configure this type of action in the mobileinit:
http://jquerymobile.com/demos/1.0b2/#/demos/1.0b2/docs/api/globalconfig.html
Let's say, in website, I want to display the notice message block whenever people click any of the link at my website more than x number of times. Is that possible to count with javascript and display the notice message block ? And can we count the refresh times also ? Or can it be only done with server side language like php ? Please kindly suggest. Thank you.
With Regards,
To do something when any link is clicked is best done with JQuery's live:
Description: Attach a handler to the
event for all elements which match the
current selector, now and in the
future.
$('a').live('click', function() {
// Live handler called.
});
Even if you add more links in run time, this will take care of it.
For counting refreshes I would do it with ajax calls on window.load event, or if you want to use new tech - store it locally with Html5. :-)
You can do that on the client. However, this will be limited to the browser. The simplest will be to store this information in cookies on the client. For instance with jQuery you could simply intercept clicks like that:
$("a").click(function() {
var clickedUrl = $(this).attr('href');
// Here you update the cookie for the count of clicks for that A URL
});
I would either count page refreshes serverside or probably call an ajax function to update the count when the page loads.
If you want to count clicks you may need to bind an event to each link and then for each indivisual button store the number of clicks in global variables...
You could register each click event on the document by using:
$(document).click(function()
{
// Check the number in the cookie and add another
// click to the cookie
});
Then you could use the jQuery cookie plugin to store that value and check it each time there is a click (in the function above).
here's the cookie plugin: https://github.com/carhartl/jquery-cookie
I threw together a quick example. If you're not worried about doing this from page to page then you don't need cookies, just store it in a variable:
http://www.webdesignandseo.net/jquery/clickcount/
Is there a way to respond to the back button being hit (or backspace being pressed) in javascript when only the location hash changes? That is to say when the browser is not communicating with the server or reloading the page.
Use the hashchange event:
window.addEventListener("hashchange", function(e) {
// ...
})
If you need to support older browsers, check out the hashChange Event section in Modernizr's HTML5 Cross Browser Polyfills wiki page.
I did a fun hack to solve this issue to my satisfaction. I've got an AJAX site that loads content dynamically, then modifies the window.location.hash, and I had code to run upon $(document).ready() to parse the hash and load the appropriate section. The thing is that I was perfectly happy with my section loading code for navigation, but wanted to add a way to intercept the browser back and forward buttons, which change the window location, but not interfere with my current page loading routines where I manipulate the window.location, and polling the window.location at constant intervals was out of the question.
What I ended up doing was creating an object as such:
var pageload = {
ignorehashchange: false,
loadUrl: function(){
if (pageload.ignorehashchange == false){
//code to parse window.location.hash and load content
};
}
};
Then, I added a line to my site script to run the pageload.loadUrl function upon the hashchange event, as such:
window.addEventListener("hashchange", pageload.loadUrl, false);
Then, any time I want to modify the window.location.hash without triggering this page loading routine, I simply add the following line before each window.location.hash = line:
pageload.ignorehashchange = true;
and then the following line after each hash modification line:
setTimeout(function(){pageload.ignorehashchange = false;}, 100);
So now my section loading routines are usually running, but if the user hits the 'back' or 'forward' buttons, the new location is parsed and the appropriate section loaded.
Check out history.js. There is a html 5 statechange event and you can listen to it.
onLocationChange may also be useful. Not sure if this is a Mozilla-only thing though, appears that it might be.
Did you took a look at this? http://developer.yahoo.com/yui/history/