Why does my function run multiple times after UpdatePanel is loaded
-
24-06-2021 - |
Question
So I want to run some javaScript function after my updatepanel is updated, so I have:
function pageLoad() {
var prm = Sys.WebForms.PageRequestManager.getInstance();
prm.add_pageLoaded(panelLoaded);
}
function panelLoaded(sender, args) {
alert("foobar");
}
With the above code, if I update the panel one time, "foobar" will be alerted one time; If I update the panel the second time, "foobar" will pop up twice; the third time I trigger the panel to update, "foobar" popped up three times... 4th time pop 4 times so on and so forth....
What caused this??
Thanks~~~
Solution 2
Thanks all, problem seem to be having too many prm instances as Sam mentioned. I added Sys.WebForms.PageRequestManager.getInstance().remove_pageLoaded(panelLoaded); after the alert() and everything is good.
OTHER TIPS
This is because pageLoad is executed during updatepanel postbacks as well. There is an easy solution:
function pageLoad(sender, eventArgs) {
// If this is being executed by ajax
if (eventArgs) {
// And this is only a partial load
if (eventArgs.get_isPartialLoad()) {
// Don't perform any further processing
return;
}
}
var prm = Sys.WebForms.PageRequestManager.getInstance();
prm.add_pageLoaded(panelLoaded);
}
This is what is happening. pageLoad
basically functions as a combination of Application.Init and PageRequestManager.EndRequest. That means it works on Application Initialization ( approximately DOM Ready ) and on each Partial PostBack
So pageLoad works on all PostBacks; full and partial.
Now you are binding up pageLoaded event again on the ScriptManager's instance on every partial postback again and again causing this behaviour.