This is some Javascript added on an .aspx page:
<Head>
<script>
function SayHello()
{
alert('Hello');
}
</script>
and here is how I am calling it from code:
protected void Page_Init(object sender, Eventargs e)
{
Page.ClientScript.RegisterStartupScript(Page.GetType(),"script","SayHello()",true);
}
The problem is that the Javascript function is called only one time, on the very first page load. I want it to be called on every post back. for example on every button click
Create a subclass of the Button control and use that on your pages. It has the OnClientClick property which you can already preset in your subclass.
I would recommend a pure JavaScript method, such as adding the call to the Javascript function in the body onload event:
<body onload="sayHello();">
Or using the jQuery library to hook onto the document's onready event:
$(document).ready(function() { sayHello(); });
You can simply use onload event:
<body onload="SayHello()">
</body>
...
If you are using UpdatePanel (AJAX), then you should register script like this:
System.Web.UI.ScriptManager.RegisterStartupScript(page, page.GetType(), "key", "SayHello()", true);
Related
My website's template is based on bootstrap and in the nav menu, I used the below code for some effects!
$('.productbar .dropdown').on('show.bs.dropdown', function (e) {
$(this).find('.dropdown-menu').first().stop(true, true).fadeIn(300);
$(this).find('.dropdown-menu').first().stop(true, true).animate({ top: "45px" }, 300);
});
$('.productbar .dropdown').on('hide.bs.dropdown', function (e) {
$(this).find('.dropdown-menu').first().stop(true, true).fadeOut(300);
$(this).find('.dropdown-menu').first().stop(true, true).animate({ top: "55px" }, 300);
$(this).find('.sub-menu').hide();
$(this).find('.left-caret').addClass("right-caret").removeClass("left-caret");
});
After firing the action button, updatepanel will fire and after this, the menu effect doesn't work!
What is the solution?
This occurs due to the Partial Postback using UpdatePanel. The Events that you subscribe for the controls are rendered partially hence the events looses. To overcome this situation you need to rebind the control events.
This is a common problem caused by mixing the conventional ASP.Net Ajax and jQuery events. When you do the partial postback, the DOM is recreated and the jQuery events are lost.
Example:
<script type="text/javscript">
// bind the events (jQuery way)
$(document).ready(function() {
bindEvents();
});
// attach the event binding function to every partial update
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(function(evt, args) {
bindEvents();
});
<script/>
Read More about PageRequest Manager on MSDN
Here bindEvents() method contains all the script that you need to reload again after Partial Page Postback.
Hope this helps you!
I faced the same problem. I got help from this link. Execute JavaScript when an UpdatePanel is updated
protected void Page_Load(object sender, EventArgs e)
{
ScriptManager.RegisterStartupScript(
upPanel,
this.GetType(),
"MyAction",
"doMyAction();",
true);
}
The first parameter is the UpdatePanel
The second parameter is a type parameter
The third parameter, “MyAction”, is a key to identify the script.
script itself.
The final parameter is a flag to indicate whether the ScriptManager should wrap your code in script tags.
If the above does not work, this should reload the events on any postback (partial or full).
Wrap your entire jquery DOM ready event function in the following:
function pageLoad() {
$(document).ready(function () {
//jquery code and events, event binding.. etc..
}); }
This can be helpful if you have many asp:update panels..
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.1/jquery.min.js"></script>
<style>
.bold {
font-weight: bold;
}
.blue {
color: blue;
}
</style>
Toggle class
<script type="text/javascript">
function ToggleClass()
{
if($(this).hasClass("bold"))
{
$(this).removeClass("bold");
}
else
{
$(this).addClass("bold");
}
}
</script>
Question:
I made one function: ToggleClass, but it does not work, what is the problem?
The reason why it doesn't work is two-fold:
No explicit binding
You're using inlined code:
Toggle class
Even though the code inside the onclick parameter is run in the right context, the function call gets invoked in the context of window, i.e. inside ToggleClass(), by default, this refers to window; it's as if ToggleClass.call(window) was written. You can bind the function to another object if you wish:
Toggle class
Using .call() you bind the current element to the function and it will work as expected.
Not enough jQuery
You're not doing things in the jQuery way.
Toggle class
...
<script>
jQuery(function($) {
$('.toggle-bold').on('click', function() {
$(this).toggleClass('bold');
return false; // prevent navigation to #
});
});
</script>
I've removed the href="javascript:void(0);" and the inlined code. Instead, I've added a class to target the anchor; if the link only occurs once inside the document, you may want to consider a unique identifier. The click handler is attached once the document is ready.
To prevent the browser from adding that pesky # at the end, I'm returning false from the click handler to stop event propagation.
Lastly. instead of hasClass(), addClass() and removeClass() I'm using toggleClass().
you need to send reference to the calling function
... onclick="ToggleClass(this);"...
<script type="text/javascript">
function ToggleClass(obj)
{
if($(obj).hasClass("bold"))
$(obj).removeClass("bold");
else
$(obj).addClass("bold");
}
however i always prefer using click function rather than inline javascript
Toggle class
<script>
$('#ToggleClass').click(function(){
if($(this).hasClass("bold"))
$(this).removeClass("bold");
else
$(this).addClass("bold");
});
</script>
Using jQuery the implementation should be as simple as using the .toggleClass() utility method:
Toggle class
<script type="text/javascript">
jQuery(function($)
{
$('#toggleme').click(function()
{
$(this).toggleClass('bold');
});
});
</script>
You're using an inline onclick handler. Your HTML:
onclick="ToggleClass();"
Is interpreted similarly to:
element.onclick = function(event) {
//`this` is available inside the onclick method
ToggleClass(); //but it is not passed to called functions automatically
}
You're just calling a function, hence the this reference is not set inside this ToggleClass execution. By "not set", I mean in the ES aspect: entering function code with an undefined this means that the this reference will point to the window object, or undefined when in strict mode.
One way to set the this reference for a function execution context is using Function.call or Function.apply:
onclick="ToggleClass.call(this, event);"
Read more about the this keyword here.
*event is not necessary with your code, but event handlers usually expect to receive an event object hence I'm passing it anyway.
However, you're already using jQuery, which sets the this reference inside event handlers and wraps the event object to make its methods cross-browser. Hence you can just add a JS hook to your element and attach listeners through jQuery:
Toggle class
<script>
$('.js-toggleClass').click(function(e) {
e.preventDefault();
$(this).toggleClass('bold');
});
</script>
Demo
I've replaced your href="javascript:void(0)" with the jQuery Event object's preventDefault() method as JavaScript does not belong inside href attributes, and used the jQuery .toggleClass() method to simplify your logic as well.
The pros of this is the separation between structure (HTML) and behavior (JS), thus keeping your code much more organized and modularized.
You are calling function ToggleClass(), but yoy are not passing parameter when calling ToggleClass() function , Pass Reference when calling ToggleClass(), otherwise buildin function exists in JQuery.
Send current object in toggleClass() function like this :
ToggleClass(this)
Toggle class
<script type="text/javascript">
function ToggleClass(abc)
{
if($(abc).hasClass("bold"))
$(abc).removeClass("bold");
else
$(abc).addClass("bold");
}
</script>
i hope it will help you
I was trying call a function on check change of checkbox, but the method I written in javascript doesn's calling. I am trying with following code
calling onchange on checkbox
<asp:CheckBox ID="CheckBox1" runat="server" onchange="fun();" />
function calling in javascript
function fun() { }
Debugger is not going thrue this function.
Also can we do it by jQuery easily?
Thanks,
jQuery:
$('#CheckBox1').on('change', fun);
plain JS
document.getElementById('CheckBox1').addEventListener('change', fun, false);
EDIT:
If the javascript code comes before the DOM element is created, you'll need some sort of DOM ready function, like window.onload in plain JS. jQuery uses document ready, and a shortcut for that is :
$(function() {
$('#CheckBox1').on('change', fun);
});
I have a pre-made layout, cannot be changed. But I must put an onload() event to <BODY>. As I said, I'm not allowed just add "onload = sdfsdf" event. Then how?
You could make a script to attach the event (i suppose that your problem is that you have no control over the html):
<script>
document.body.onload = function(){};
</script>
Use JQuery:
$(document).ready(function() {
});
http://docs.jquery.com/Tutorials:Introducing_%24%28document%29.ready%28%29
You can register events on the body through a (java)script using:
document.body.<event name> = function(){ // whatever your function does };
Use window.onload = function(){ ... }. That has the equivalent result as <body onload="...">.
put all your code in an function that autoexecute:
(function () {
//your code here
})();
and put it at the end of the body.
If you want to make everything by yourself, without jQuery. MDN addEventListener.
target.addEventListener(type, listener, useCapture<Optional>);
Depending on the required effect, listener:
DOMContentLoaded - loading of the DOM
load - loading of all the resource on the page - useful if the page contains large images
I'm using jQuery to wire up some mouseover effects on elements that are inside an UpdatePanel. The events are bound in $(document).ready . For example:
$(function() {
$('div._Foo').bind("mouseover", function(e) {
// Do something exciting
});
});
Of course, this works fine the first time the page is loaded, but when the UpdatePanel does a partial page update, it's not run and the mouseover effects don't work any more inside the UpdatePanel.
What's the recommended approach for wiring stuff up in jQuery not only on the first page load, but every time an UpdatePanel fires a partial page update? Should I be using the ASP.NET ajax lifecycle instead of $(document).ready?
An UpdatePanel completely replaces the contents of the update panel on an update. This means that those events you subscribed to are no longer subscribed because there are new elements in that update panel.
What I've done to work around this is re-subscribe to the events I need after every update. I use $(document).ready() for the initial load, then use Microsoft's PageRequestManager (available if you have an update panel on your page) to re-subscribe every update.
$(document).ready(function() {
// bind your jQuery events here initially
});
var prm = Sys.WebForms.PageRequestManager.getInstance();
prm.add_endRequest(function() {
// re-bind your jQuery events here
});
The PageRequestManager is a javascript object which is automatically available if an update panel is on the page. You shouldn't need to do anything other than the code above in order to use it as long as the UpdatePanel is on the page.
If you need more detailed control, this event passes arguments similar to how .NET events are passed arguments (sender, eventArgs) so you can see what raised the event and only re-bind if needed.
Here is the latest version of the documentation from Microsoft: msdn.microsoft.com/.../bb383810.aspx
A better option you may have, depending on your needs, is to use jQuery's .on(). These method are more efficient than re-subscribing to DOM elements on every update. Read all of the documentation before you use this approach however, since it may or may not meet your needs. There are a lot of jQuery plugins that would be unreasonable to refactor to use .delegate() or .on(), so in those cases, you're better off re-subscribing.
<script type="text/javascript">
function BindEvents() {
$(document).ready(function() {
$(".tr-base").mouseover(function() {
$(this).toggleClass("trHover");
}).mouseout(function() {
$(this).removeClass("trHover");
});
}
</script>
The area which is going to be updated.
<asp:UpdatePanel...
<ContentTemplate
<script type="text/javascript">
Sys.Application.add_load(BindEvents);
</script>
*// Staff*
</ContentTemplate>
</asp:UpdatePanel>
User Control with jQuery Inside an UpdatePanel
This isn't a direct answer to the question, but I did put this solution together by reading the answers that I found here, and I thought someone might find it useful.
I was trying to use a jQuery textarea limiter inside of a User Control. This was tricky, because the User Control runs inside of an UpdatePanel, and it was losing its bindings on callback.
If this was just a page, the answers here would have applied directly. However, User Controls do not have direct access to the head tag, nor did they have direct access to the UpdatePanel as some of the answers assume.
I ended up putting this script block right into the top of my User Control's markup. For the initial bind, it uses $(document).ready, and then it uses prm.add_endRequest from there:
<script type="text/javascript">
function BindControlEvents() {
//jQuery is wrapped in BindEvents function so it can be re-bound after each callback.
//Your code would replace the following line:
$('#<%= TextProtocolDrugInstructions.ClientID %>').limit('100', '#charsLeft_Instructions');
}
//Initial bind
$(document).ready(function () {
BindControlEvents();
});
//Re-bind for callbacks
var prm = Sys.WebForms.PageRequestManager.getInstance();
prm.add_endRequest(function() {
BindControlEvents();
});
</script>
So... Just thought someone might like to know that this works.
Upgrade to jQuery 1.3 and use:
$(function() {
$('div._Foo').live("mouseover", function(e) {
// Do something exciting
});
});
Note: live works with most events, but not all. There is a complete list in the documentation.
You could also try:
<asp:UpdatePanel runat="server" ID="myUpdatePanel">
<ContentTemplate>
<script type="text/javascript" language="javascript">
function pageLoad() {
$('div._Foo').bind("mouseover", function(e) {
// Do something exciting
});
}
</script>
</ContentTemplate>
</asp:UpdatePanel>
,since pageLoad() is an ASP.NET ajax event which is executed each time the page is loaded at client side.
My answer?
function pageLoad() {
$(document).ready(function(){
etc.
Worked like a charm, where a number of other solutions failed miserably.
I would use one of the following approaches:
Encapsulate the event binding in a function and run it every time you update the page. You can always contain the event binding to specific elements so as not to bind events multiple times to the same elements.
Use the livequery plug-in, which basically performs method one for you auto-magically. Your preference may vary depending on the amount of control you want to have on the event binding.
function pageLoad() is very dangerous to use in this situation. You could have events become wired multiple times. I would also stay away from .live() as it attaches to the document element and has to traverse the entire page (slow and crappy).
The best solution I have seen so far is to use jQuery .delegate() function on a wrapper outside the update panel and make use of bubbling. Other then that, you could always wire up the handlers using Microsoft's Ajax library which was designed to work with UpdatePanels.
When $(document).ready(function (){...}) not work after page post back then use JavaScript function pageLoad in Asp.page as follow:
<script type="text/javascript" language="javascript">
function pageLoad() {
// Initialization code here, meant to run once.
}
</script>
I had a similar problem and found the way that worked best was to rely on Event Bubbling and event delegation to handle it. The nice thing about event delegation is that once setup, you don't have to rebind events after an AJAX update.
What I do in my code is setup a delegate on the parent element of the update panel. This parent element is not replaced on an update and therefore the event binding is unaffected.
There are a number of good articles and plugins to handle event delegation in jQuery and the feature will likely be baked into the 1.3 release. The article/plugin I use for reference is:
http://www.danwebb.net/2008/2/8/event-delegation-made-easy-in-jquery
Once you understand what it happening, I think you'll find this a much more elegant solution that is more reliable than remembering to re-bind events after every update. This also has the added benefit of giving you one event to unbind when the page is unloaded.
FWIW, I experienced a similar issue w/mootools. Re-attaching my events was the correct move, but needed to be done at the end of the request..eg
var prm = Sys.WebForms.PageRequestManager.getInstance();
prm.add_endRequest(function() {...
Just something to keep in mind if beginRequest causes you to get null reference JS exceptions.
Cheers
pageLoad = function () {
$('#div').unbind();
//jquery here
}
The pageLoad function is perfect for this case since it runs on the initial page load and every updatepanel async postback. I just had to add the unbind method to make the jquery work on updatepanel postbacks.
http://encosia.com/document-ready-and-pageload-are-not-the-same/
My answer is based on all the expert comments above, but below is the following code that anyone can use to make sure on each postback and on each asynchronous postback the JavaScript code will still be executed.
In my case, I had a user control within a page. Just paste the below code in your user control.
<script type="text/javascript">
var prm = Sys.WebForms.PageRequestManager.getInstance();
prm.add_endRequest(EndRequestHandler);
function EndRequestHandler(sender, args) {
if (args.get_error() == undefined) {
UPDATEPANELFUNCTION();
}
}
function UPDATEPANELFUNCTION() {
jQuery(document).ready(function ($) {
/* Insert all your jQuery events and function calls */
});
}
UPDATEPANELFUNCTION();
</script>
Update Panel always replaces your Jquery with its inbuilt Scriptmanager's scripts after every load. Its better if you use pageRequestManager's instance methods like this...
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(onEndRequest)
function onEndRequest(sender, args) {
// your jquery code here
});
it will work fine ...
Use below script and change the body of the script accordingly.
<script>
//Re-Create for on page postbacks
var prm = Sys.WebForms.PageRequestManager.getInstance();
prm.add_endRequest(function () {
//your codes here!
});
</script>
In response to Brian MacKay's answer:
I inject the JavaScript into my page via the ScriptManager instead of putting it directly into the HTML of the UserControl. In my case, I need to scroll to a form that is made visible after the UpdatePanel has finished and returned. This goes in the code behind file. In my sample, I've already created the prm variable on the main content page.
private void ShowForm(bool pShowForm) {
//other code here...
if (pShowForm) {
FocusOnControl(GetFocusOnFormScript(yourControl.ClientID), yourControl.ClientID);
}
}
private void FocusOnControl(string pScript, string pControlId) {
ScriptManager.RegisterStartupScript(this.Page, this.Page.GetType(), "focusControl_" + pControlId, pScript, true);
}
/// <summary>
/// Scrolls to the form that is made visible
/// </summary>
/// <param name="pControlId">The ClientID of the control to focus on after the form is made visible</param>
/// <returns></returns>
private string GetFocusOnFormScript(string pControlId) {
string script = #"
function FocusOnForm() {
var scrollToForm = $('#" + pControlId + #"').offset().top;
$('html, body').animate({
scrollTop: scrollToForm},
'slow'
);
/* This removes the event from the PageRequestManager immediately after the desired functionality is completed so that multiple events are not added */
prm.remove_endRequest(ScrollFocusToFormCaller);
}
prm.add_endRequest(ScrollFocusToFormCaller);
function ScrollFocusToFormCaller(sender, args) {
if (args.get_error() == undefined) {
FocusOnForm();
}
}";
return script;
}
Sys.Application.add_load(LoadHandler); //This load handler solved update panel did not bind control after partial postback
function LoadHandler() {
$(document).ready(function () {
//rebind any events here for controls under update panel
});
}
For anyone else in my situation, I was trying to get jquery document ready function to work for a DevExpress ASPxCallbackPanel and nothing above (to-date) worked. This is what did work for me.
<script>
function myDocReadyFunction(){ /* do stuff */ }
</script>
<dx:ASPxCallbackPanel ID="myCallbackPanel" ... >
<ClientSideEvents EndCallback="function(){ myDocReadyFunction();}">
</ClientSideEvents>
<PanelCollection ...>
</dx:ASPxCallbackPanel>