Event handling is a coding style about handling messages between a source and one or more subscribers. A point listener in the source provide a way which subscribed code can consume messages raised from the source.
Questions tagged [event-handling]
12746 questions
267
votes
10 answers
What is DOM Event delegation?
Can anyone please explain event delegation in JavaScript and how is it useful?
Xenon
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265
votes
1 answer
How to remove a lambda event handler
I recently discovered that I can use lambdas to create simple event handlers. I could for example subscribe to a click event like this:
button.Click += (s, e) => MessageBox.Show("Woho");
But how would you unsubscribe it?
Svish
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253
votes
16 answers
Which Python packages offer a stand-alone event system?
I am aware of pydispatcher, but there must be other event-related packages around for Python.
Which libraries are available?
I'm not interested in event managers that are part of large frameworks, I'd rather use a small bare-bones solution that I…
Josip
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243
votes
41 answers
Detecting Browser Autofill
How do you tell if a browser has auto filled a text-box? Especially with username & password boxes that autofill around page load.
My first question is when does this occur in the page load sequence? Is it before or after document.ready?
Secondly…
Undefined
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217
votes
7 answers
jQuery equivalent of JavaScript's addEventListener method
I'm trying to find the jQuery equivalent of this JavaScript method call:
document.addEventListener('click', select_element, true);
I've gotten as far as:
$(document).click(select_element);
but that doesn't achieve the same result, as the last…
Bungle
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207
votes
10 answers
How can I remove a JavaScript event listener?
I'm trying to remove an event listener inside of a listener definition:
canvas.addEventListener('click', function(event) {
click++;
if(click == 50) {
// remove this event listener here!
}
// More code here ...
How could I do…
thomas
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205
votes
4 answers
Do event handlers stop garbage collection from occurring?
If I have the following code:
MyClass pClass = new MyClass();
pClass.MyEvent += MyFunction;
pClass = null;
Will pClass be garbage collected? Or will it hang around still firing its events whenever they occur? Will I need to do the following in…
Mark Ingram
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201
votes
5 answers
Why and How to avoid Event Handler memory leaks?
I just came to realize, by reading some questions and answers on StackOverflow, that adding event handlers using += in C# (or i guess, other .net languages) can cause common memory leaks...
I have used event handlers like this in the past many…
gillyb
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188
votes
5 answers
How to pass event as argument to an inline event handler in JavaScript?
// this e works
document.getElementById("p").oncontextmenu = function(e) {
e = e || window.event;
var target = e.target || e.srcElement;
console.log(target);
};
// this e is undefined
function doSomething(e) {
e = e || window.event;
var…
user1643156
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171
votes
8 answers
How do I add a simple onClick event handler to a canvas element?
I'm an experienced Java programmer but am looking at some JavaScript/HTML5 stuff for the first time in about a decade. I'm completely stumped on what should be the simplest thing ever.
As an example I just wanted to draw something and add an event…
Jer
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163
votes
8 answers
How can I be notified when an element is added to the page?
I want a function of my choosing to run when a DOM element is added to the page. This is in the context of a browser extension, so the webpage runs independently of me and I cannot modify its source. What are my options here?
I guess that, in…
Kevin Burke
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162
votes
4 answers
145
votes
6 answers
Handling a Menu Item Click Event - Android
I want to create an intent that starts a new activity once a Menu Item is clicked, but I'm not sure how to do this. I've been reading through the android documentation, but my implementation isn't correct..and some guidance in the right direction…
Jade Byfield
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143
votes
8 answers
jQuery: more than one handler for same event
What happens if I bind two event handlers to the same event for the same element?
For example:
var elem = $("...")
elem.click(...);
elem.click(...);
Does the last handler "win", or will both handlers be run?
flybywire
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135
votes
5 answers
Detecting CTRL+C in Node.js
I got this code from a different SO question, but node complained to use process.stdin.setRawMode instead of tty, so I changed it.
Before:
var tty = require("tty");
process.openStdin().on("keypress", function(chunk, key) {
if(key && key.name ===…
user3025492
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