How to keep scroll position independent of postback? - javascript

I have a regular time interval event in javascript which clicks an asp button. The application is a common chat room and I have to refresh the gridview (which is inside a panel) to check for new chats. But everytime the button is clicked and gridview is refreshed the panel scrolls up to the top (i.e., scrollTop value becomes 0). I have tried this but to no avail:-
<script type="text/javascript">
function refresh() {
setInterval(function () {
var xtop = document.getElementById("Panel1").scrollTop;
document.getElementById("Button2").click();
document.getElementById("Panel1").scrollTop = xtop;
}, 1000);
}
</script>

If you want to store the scroll position between postbacks, in your refresh() function you can store the scroll position value in a hidden field that you put somewhere in your HTML: <input type="hidden" id="scroll"></input> using JavaScript
document.getElementById("scroll").value = document.getElementById("Panel1").scrollTop;
There are other options to persist data such as cookies and the ASP.NET ViewState, but a hidden field is simplest for this purpose. You can then read this value from the hidden field upon loading the DOM and scroll the window to that position.
However, if you are posting back every second to check for new messages, you probably have a bigger problem. This kind of functionality is better done asynchronously with AJAX. It will need a bit of looking into as I'm not sure of your implementation here, but essentially you will use JavaScript to ask the server if there are new messages and load them from the server asynchronously, thereby eliminating the use of postbacks.
Here is Mozilla's introduction to AJAX.

Related

Can we remove click event without calling it?

I am having problem in overriding the pagination code given by grid. What I need to do is kind of hack the pagination given by my grid.
We are having a lot of records. So, what we are doing we are loading records to a threshold limit.
So, lets assume the threshold limit is 50 and page size is 10 so there will be 5 pages. So, when user comes to 5th page next button provided by the grid will be disabled.
So, what we need to do we need to make it enable and if user clicks on it I need make ajax call and load another 50 records(threshold limit) in the grid.
After that I need to disable this event so that next time user clicks it should not do the make ajax call and it should work like previously (by going from 1st page to 2nd page and so on)
All the above things mentioned I am able to do. But here problem comes when user goes to 5th page and go back to some other page let say 3 without clicking next button. Now, after going to 3rd page
when user clicks on the next page button it is making ajax call as I have make the button enable when user comes to 5th page and provided a click event to it.
So even if I provide a condition to run only on when grid current page is 5 then also it is running because after going to 5th page I will make button enable and bind and event. So, as I provided the event it will run without even specifying the condition.
How do I make the click event work as default and only when the user is at 5 it will make the ajax call.
This is my code -
///grid Current page will tell us which page we are in the grid.
if(gridCurrentPage==5){
query(".dojoxGridWardButton").forEach(function(element) {
query(".dojoxGridnextPageBtnDisable").replaceClass("dojoxGridnextPageBtn", "dojoxGridnextPageBtnDisable");
query(".dojoxGridlastPageBtnDisable").replaceClass("dojoxGridlastPageBtn", "dojoxGridlastPageBtnDisable");
});
callNextButton(gridCurrentPage)
}
And this is the function.
function callNextButton(gridCurrentPage) {
var target = dojo.query(".dojoxGridnextPageBtn");
var signal = on(target, "click", function(event){ ///Adding click event
if (gridCurrentPage ==5 ) {
var deferred = new dojo.Deferred();
setTimeout(function() {
deferred.callback({
called: true
})
}, 2000);
if (checking some conditions) {
////////doing Ajax call
deferred.then(function() {
//calling a callback
})
},
error: function(e) {}
};
})
signal.remove(); //Removing click event
}
Note : My grid is enhanced grid which is part of dojo toolkit. But probably its a design issue so, any comments/advices are welcome.
I really need an advice here. Please anyone can find the problem where it is it will be reqlly helpful.

javascript history.back losses the search result

Page A:
$(document).ready(function () {
bindData();
});
function bindData() {
$('#searchbtn').bind('click', function () { SearchResult(); });
}
function SearchResult() {
ajax call...
}
Page A HTML:
<input type="button" id="searchbtn" />
Page B Details---> this page comes after selecting a specific search result from page A search list
Back<br />
Now when I go back to the Page A I can see my search criteria's as they were selected but the result Div is gone. What I am trying to do is I want the search list to stay when the Page comes back.
I think what I can do here is some how call the searchbtn click event again when the page comes back so the list will come-up again. Can anyone tell me how to fire the searchbtn click event only when the page comes back from Page B. or point me in the right way of doing this..
Thanks
The Browser Back button has long been problematic with AJAX. There are scripts, workarounds, and techniques out there (depending on the framework that you want to use).
Since it appears that you are using jQuery (based on your posted JavaScript syntax), here is a link to another Stackoverflow post regarding back button jQuery plugins.
history.back() will return you to the last URL visited, meaning that any ajax calls made during the user's visit will not be automatically repeated. Your browser may automatically restore your form selections, but the SearchResults() function is only called by a click event, not a selection event.
You can bind URLs to ajax states using a framework like sammy.js. That way, history.back() would take you to a URL associated with SearchResults().
function bindData() {
var chkinput1 = $("input:checkbox[name=x]:checked").length;
var chkinput2 = $("input:checkbox[name=y]:checked").length;
if (chkinput1 > 0 && chkinput2 > 0) {
SearchResult();
}
$('#searchbtn').bind('click', function () { SearchResult(); });
}
I know this is the worst way to achieve this result but I think instead of using any other plugins to add complexity we will go with this for now. If anyone else is looking for the same question let me tell you again this is not the best practice as on returning back to the history we are calling the search result again depending upon the cached input selection of checkboxes and generating the whole ajax call again to display the list. On the first request I am caching the list and setting sliding expiration so its not taking anytime to comeback and so everyone lives happily.

Javascript - Reload page after form submit with target="_blank"

I'm trying to achive the following:
On page A we have an access restricted Link to page B. The access restriction is handled on the server side in PHP.
When a user clicks on this link to page B we display a modal dialogue on page A (via javascript) with a form, having the link's href (B) as the action. (To give the user an immediate feedback. The fallback is to redirect him to a login form that redirects him to the site he wants to access.)
This system works quite well.
But now comes my question:
We have access restricted links that should be opened in a new window.
Now if I use target="_blank" on the form the user stays logged out on the page he came from (A), that is still open in the background.
Is there a way to reload the page (A, in the background) right after the form has been submitted to the new window (B)?
My first idea was to use window.location.reload(); in the submit handler on page A.
This didn't work in chrome and from what I understand could create a race condition.
Another idea would be to log the user in via an ajax call and open a new window through javascript. Is there a way to do this without having to deal with pop-up blockers?
I implemented the idea of lostsource (see below) with one slight addition.
As I need to reload only once, the timer of setInterval can be stopped if the cookie changed.
var ri=setInterval(function() {
if(oldCookie != document.cookie) {
// assuming a login happened, reload page
clearInterval(ri);
window.location.reload();
}
},1000); // check every second
I still love the idea. stackoverflow is awsome!
Assuming you're storing PHP session information inside a cookie, you might be able to monitor your document.cookie for changes.
Before submitting the form store the value of the current cookie and monitor it for changes with a timer:
form.onsubmit = function() {
var oldCookie = document.cookie;
var cookiePoll = setInterval(function() {
if(oldCookie != document.cookie) {
// stop polling
clearInterval(cookiePoll);
// assuming a login happened, reload page
window.location.reload();
}
},1000); // check every second
}
On the parent page, do you have any visual/functional changes because of the login? As in any new actions possible?
If not, then you dont have to do anything as you would be checking for login on every action from the parent page, you can check for permissions along with that.
If there are changes or additional functionalities, you can call a javascript function in the parent, say reloadMe, using window.opener.reloadMe()
Why not just a simple setTimeout
setTimeout(function(){ location.reload(); }, 1000);
It is a bit hacky, but seems appropriate for your situation.

How to check page is reloading or refreshing using jquery or javascript?

I have to do some kind of operation on the page refresh or reload. that is when I hit next page or Filter or refresh on the grid. I need to show some confirmation box over this Events.
is there any event which can tell you page is doing filer? refresh or paging? using javascript?
Thanks
If it is refreshing (or the user is leaving the website/closing the browser), window.onunload will fire.
// From MDN
window.onunload = unloadPage;
function unloadPage()
{
alert("unload event detected!");
}
https://developer.mozilla.org/en/DOM/window.onunload
If you just want a confirmation box to allow them to stay, use this:
window.onbeforeunload = function() {
return "Are you sure you want to navigate away?";
}
You can create a hidden field and set its value on first page load. When the page is loaded again, you can check the hidden field. If it's empty then the page is loaded for the first time, else it's refreshed. Some thing like this:
HTML
<body onLoad="CheckPageLoad();">
<input type="hidden" name="visit" id="visit" value="" />
</body>
JS
function CheckPageLoad() {
if (document.getElementById("visit").value == "") {
// This is a fresh page load
document.getElementById("visit").value = "1";
}
else {
// This is a page refresh
}
}​
There are some clarification notes on wrestling with this I think are critical.
First, the refresh/hidden field system works on the beginning of the new page copy and after, not on leaving the first page copy.
From my research of this method and a few others, there is no way, primarily due to privacy standards, to detect a refresh of a page during unload or earlier. only after the load of the new page and later.
I had a similar issue request, but basically it was terminate session on exit of page, and while looking through that, found that a browser treats a reload/refresh as two distinct pieces:
close the current window (fires onbeforeunload and onunload js events).
request the page as if you never had it. Session on server of course has no issue, but no querystring changes/added values to the page's last used url.
These happen in just that order as well. Only a custom or non standard browser will behave differently.
$(function () {
if (performance.navigation.type == 1) {
yourFunction();
}
});
More about PerformanceNavigation object returned by performance.navigation

RadScheduler update interval

I'm using RadScheduler for my project. In the scheduler, I need a periodical update, so in my javascript, I set interval for a method that call rebind() on the RadScheduler for every 60 seconds. The problem is that, when my user open the advanced form, the rebind() method makes the form disappear. How can I detect AdvancedForm opening and closing event so that I can stop /restart the timer ?
Thank you in advance.
While there is an event for when the RadScheduler opens its Edit form, called OnClientFormCreated, there is not one for when the edit form closes. There are ways to do this though, but you have do add some additional code.
When you think about it there are several different items that can lead to the form closing - the user can click on the close icon at the top right (or left, depending on your orientation) of the window, they can click cancel, or they can hit save.
Keeping that in mind, we can take a look at this demo, which shows the Advanced Edit Form in action, and also has some JavaScript pre-written for us.
Within the schedulerFormCreated() function we can do the following:
function schedulerFormCreated(scheduler, eventArgs) {
// Create a client-side object only for the advanced templates
var mode = eventArgs.get_mode();
if (mode == Telerik.Web.UI.SchedulerFormMode.AdvancedInsert ||
mode == Telerik.Web.UI.SchedulerFormMode.AdvancedEdit) {
// Initialize the client-side object for the advanced form
var formElement = eventArgs.get_formElement();
var cancelButton = $("[id$='_CancelButton']");
cancelButton.on("click", formClosed);
var templateKey = scheduler.get_id() + "_" + mode;
....
And then we have the formClosed event:
function formClosed(eventArgs) {
}
in formClosed you can just create your logic for resuming the timer, while in schedulerFormCreated you can directly call the function that stops the timer right after that if-statement.
In case you're wondering what we're doing here we're simply grabbing an instance of the jQuery object representing the element with an id that ends with _CancelButton (we're not interested in the beginning part) and then just binding to the click event using the .on() jQuery function.
To get an instance of the save button you just have to use _UpdateButton, and for the close icon it is _AdvancedEditCloseButton. Keep in mind that any element that ends with these substrings will be selected, so if you want to be more specific I recommend inspecting the elements of your advanced form using FireBug or the Chrome Dev tools to get their ID and plug that into the selector above.
This should allow you to get the functionality you're looking for.

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