how to execute everything in jquery when something is done [duplicate] - javascript

Is there a way to have keyup, keypress, blur, and change events call the same function in one line or do I have to do them separately?
The problem I have is that I need to validate some data with a db lookup and would like to make sure validation is not missed in any case, whether it is typed or pasted into the box.

You can use .on() to bind a function to multiple events:
$('#element').on('keyup keypress blur change', function(e) {
// e.type is the type of event fired
});
Or just pass the function as the parameter to normal event functions:
var myFunction = function() {
...
}
$('#element')
.keyup(myFunction)
.keypress(myFunction)
.blur(myFunction)
.change(myFunction)

As of jQuery 1.7, the .on() method is the preferred method for attaching event handlers to a document. For earlier versions, the .bind() method is used for attaching an event handler directly to elements.
$(document).on('mouseover mouseout',".brand", function () {
$(".star").toggleClass("hovered");
})

I was looking for a way to get the event type when jQuery listens for several events at once, and Google put me here.
So, for those interested, event.type is my answer :
$('#element').on('keyup keypress blur change', function(event) {
alert(event.type); // keyup OR keypress OR blur OR change
});
More info in the jQuery doc.

You can use bind method to attach function to several events. Just pass the event names and the handler function as in this code:
$('#foo').bind('mouseenter mouseleave', function() {
$(this).toggleClass('entered');
});
Another option is to use chaining support of jquery api.

Is there a way to have keyup, keypress, blur, and change events call the same function in one line?
It's possible using .on(), which accepts the following structure: .on( events [, selector ] [, data ], handler ), so you can pass multiple events to this method. In your case it should look like this:
$('#target').on('keyup keypress blur change', function(e) {
// "e" is an event, you can detect the type of event using "e.type"
});
And here is the live example:
$('#target').on('keyup keypress blur change', function(e) {
console.log(`"${e.type.toUpperCase()}" event happened`)
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input id="target">

If you attach the same event handler to several events, you often run into the issue of more than one of them firing at once (e.g. user presses tab after editing; keydown, change, and blur might all fire).
It sounds like what you actually want is something like this:
$('#ValidatedInput').keydown(function(evt) {
// If enter is pressed
if (evt.keyCode === 13) {
evt.preventDefault();
// If changes have been made to the input's value,
// blur() will result in a change event being fired.
this.blur();
}
});
$('#ValidatedInput').change(function(evt) {
var valueToValidate = this.value;
// Your validation callback/logic here.
});

This is how i do it.
$("input[name='title']").on({
"change keyup": function(e) {
var slug = $(this).val().split(" ").join("-").toLowerCase();
$("input[name='slug']").val(slug);
},
});

You could define the function that you would like to reuse as below:
var foo = function() {...}
And later you can set however many event listeners you want on your object to trigger that function using on('event') leaving a space in between as shown below:
$('#selector').on('keyup keypress blur change paste cut', foo);

The answer by Tatu is how I would intuitively do it, but I have experienced some problems in Internet Explorer with this way of nesting/binding the events, even though it is done through the .on() method.
I havn't been able to pinpoint exactly which versions of jQuery this is the problem with. But I sometimes see the problem in the following versions:
2.0.2
1.10.1
1.6.4
Mobile 1.3.0b1
Mobile 1.4.2
Mobile 1.2.0
My workaround have been to first define the function,
function myFunction() {
...
}
and then handle the events individually
// Call individually due to IE not handling binds properly
$(window).on("scroll", myFunction);
$(window).on("resize", myFunction);
This is not the prettiest solution, but it works for me, and I thought I would put it out there to help others that might stumble upon this issue

$("element").on("event1 event2 event..n", function() {
//execution
});
This tutorial is about handling multiple events.

It's simple to implement this with the built-in DOM methods without a big library like jQuery, if you want, it just takes a bit more code - iterate over an array of event names, and add a listener for each:
function validate(event) {
// ...
}
const element = document.querySelector('#element');
['keyup', 'keypress', 'blur', 'change'].forEach((eventName) => {
element.addEventListener(eventName, validate);
});
If you'd want to mimic adding to more than 1 element:
const elements = document.querySelectorAll('.commonSelector');
['keyup', 'keypress', 'blur', 'change'].forEach((eventName) => {
elements.forEach(element => {
element.addEventListener(eventName, validate);
});
});

Instead of:
$('#element').on('keyup keypress blur change', function(e) {
// e.type is the type of event fired
});
You can use:
$('#element').on('input', function(e) {
// e.type is the type of event fired
});
input is trigerred for keyup keypress blur change events even for paste!

But to prevent multiple triggering:
var a;
var foo = function() {
clearTimeout(a);
a=setTimeout(function(){
//your code
console.log("Runned")
},50);
}
$('textarea').on('blur change', foo);

Related

add change() event to an existing click() function without triggering the first event

I have a JQuery click() function and I need to add the change() event for another element (that must only trigger the change() event).
How can I combine it, but make this extra element only trigger one of the two events?
$('body').on('click change', '.click-1, .click-2, :checkbox, .change', function()
I added the change event and the change class. Also for the checkboxes, are they going to trigger the two events? (could it be a problem?).
Is there any way to make the element only trigger that event and not the click()?
I just need to find a way to not repeat the same code (50 lines) twice.
EDIT: Fix (thanks to #somethinghere):
$('body').on('click change', '.click-1, .click-2, :checkbox, .change', function(event) {
if (event.type == 'click' && $(this).hasClass( 'change' )) {
event.preventDefault();
event.stopImmediatePropagation();
return;
}
// more code
});
A proper fix should be use click() only for the buttons.
Simple, store the function and pass the function as a parameter twice:
function yourfunctionname(e) {
...
}
$('body').on('click', '.click-1, .click-2', yourfunctionname)
.on('change', ':checkbox, .change', yourfunctionname);

Turning Off Specific Click Event

JSFIDDLE: http://jsfiddle.net/w55usyqk/
When you click the div there are two separate click events fired. They print out "click" and "clicked" respectively in the console log.
$("div").on("click", function() { console.log("click"); });
$("div").on("click", function() { console.log("clicked"); });
If you tap on the button it will remove both event declarations from the div object
$("button").on("click", function() { $("div").off("click"); });
However, what if I just needed to remove a single click event? Is this stored in some sort of event array where I could do something along the lines of $("div").off("click")[1]; or is it impossible to turn off one without turning off the other as well?
I did try looking for the answer if it's been posted before. I think this is one of those questions that's hard to word, so though there may be an answer out there, it's difficult to pin down.
You can use namespaces to easily do this. When you create your event handlers, add the namespace after the event. Ex:
$("div").on("click.namespace1", function() { console.log("click"); });
$("div").on("click.namespace2", function() { console.log("clicked"); });
then for your button, use the namespace of the event to remove:
// remove only the event for namespace2
$("button").on("click", function() { $("div").off(".namespace2"); });
jsFiddle example
Some more on namespaces for events:
An event name can be qualified by event namespaces that simplify
removing or triggering the event. For example, "click.myPlugin.simple"
defines both the myPlugin and simple namespaces for this particular
click event. A click event handler attached via that string could be
removed with .off("click.myPlugin") or .off("click.simple") without
disturbing other click handlers attached to the elements. Namespaces
are similar to CSS classes in that they are not hierarchical; only one
name needs to match. Namespaces beginning with an underscore are
reserved for jQuery's use.
Use named functions as event handlers, so you can then reference what handler you want to unbind:
function clicOne() {console.log("click");};
function clicTwo() {console.log("clicked");};
$("div").on("click", clickOne);
$("div").on("click", clicTwo);
$("button").on("click", function() { $("div").off("click", clickOne); });

Access all event listeners in Javascript

I want to do something like this:
function('string', function2(){})
where I leave the to user to write what he wants in the string parameter and than execute function2.
The catch is here: string is an event listener. When the user writes click, I want to call onClick(), when the user writes mouse I want to call onMouseOver and so on.
I have in mind doing something with case, but how can I access all event listeners?
You should use addEventListener.
element.addEventListener("string", function() {}, false);
However, in the case of IE <= 8, you will need to use attachEvent as it does not follow the standard:
element.attachEvent("string", function() {});
Finally, as kybernetikos mentions in his comment, you can then use a simple dictionary to map mouse to mouseover.
If you wish to fire events, you should use dispatchEvent.
If you add the event listeners using the old model (i.e. elem.onclick = function(){ /* */ };), you can use
elem['on' + event]();
Keep in mind that this only fires the event listeners, but doesn't create an event (e.g. it won't bubble).
If you won't to create a event, which fires event listeners added using addEventlistener, and bubbles, and does all things a real event does, you must
Create your event using event constructors: Event or CustomEvent
Fire it with dispatchEvent
See MDN page for more information and examples.
you can use .trigger to do this. Check out this example in jsfiddle. type "dblclick" in the input box.
http://jsfiddle.net/jspatel/Suj4H/1/
<input id="writehere"> </input>
$('#writehere').dblclick(function() {
alert ('dblclick');
});
$('#writehere').bind('keypress', function(e) {
if(e.keyCode==13){
$(this).trigger( $(this).val() );
}
});

jQuery .one() with same function for different events on different elements

I have an introduction on my page which shall disappear when a key is pressed or a certain elements is clicked on. I'll use the same function for both events but as the page is heavily modified the event shall fire only once regardless which way it was triggered.
My function:
function start() {
$('.intro').remove();
$('.something-else').show();
}
How I bind the events:
$('body').keypress(start);
$('.intro').click(start);
If the events were the same I could say
$('body, .intro').one('click', start);
If both events were to happen to the same element I could say:
$('.intro').one('click keypress', start);
How to combine both things: having different elements and different events and the function must only be called once?
The simplest solution would be to store whether your function has been called or not.
var started = false;
function start() {
if(started) return;
$('.intro').remove();
$('.something-else').show();
started = true;
}
Then your function can only be called once, every other call will be ignored.
I don't think this solution is a clean as an explicit approach, but is done using a combination of .one() and .trigger(). Because you call $(".intro").remove() on one of the bound items the event handler is implicitly unbound. Sample Fiddle
Excluding the html seen in fiddle, this is the code.
// Your event handler
function start() {
$("#intro").remove();
$("#main").show();
console.log("start handler called");
}
// Handle the keypress event
$("body").one( "keypress", start );
// Allow user to click through the intro, but trigger the keypress handler on the body which is a one-time event handler)
$("#intro").one( "click", function () { $("body").trigger( "keypress" ); });
Use two lines of code and be done ;)
$('body').one('keypress', start);
$('.intro').one('click', start);
Edit:
You should manually unbind the other callback, lest it runs later, unexpectedly.

jQuery Multiple Events

I know how to bind multiple events and all that stuff. What I want to do is have multiple events occur to trigger a function.
Like
$(this).click and $(this).mousemove triggers a function
Is there a way to do this? Is it possible or am I just dreaming.
With a better understanding now, one thing you could do is have one event bind and unbind the other:
Example: http://jsfiddle.net/ZMeUv/
$(myselector).mousedown( function() {
$(document).mousemove(function() {
// do something
});
$(document).mouseup(function() {
$(this).unbind(); // unbind events from document
});
});
This prevents the mousemove from constantly firing when you have no need for it.
You can use jQuery's special events to package everything nicely and optimize things in the process. A mousedown and mousemove combo also commonly goes by the name "drag", so here's an example of creating a drag event that you can bind to elements. Note, that this code is specific to jQuery 1.4.2
One of the advantages to using this is that you only bind the mousemove, mouseout, and mousedown handlers once each element, no matter how many times that element is bound to the drag event. Now this isn't the most optimal way of doing it, and you can setup just 3 handlers on the document and manage everything with it, which is equally easy to do with the special events API. It just provides a nicely packaged way of building complex interactions than would be possible with just native events or custom events, in the jQuery sense.
$("..").bind("drag", function() {
...
});
I will try and add more documentation on what's actually going on, as it looks pretty unintuitive, I must confess. Checkout another nice article on the topic.
See an example of this here. To create this custom special event, use:
jQuery.event.special.drag = {
// invoked each time we bind drag to an element
add: function(obj) {
var originalHandler = obj.handler;
obj.handler = function(event) {
var el = jQuery(this);
if(el.data('mousePressed')) {
return originalHandler.apply(this, arguments);
}
};
},
// invoked only the first time drag is bound per element
setup: function(data, namespaces) {
var el = jQuery(this);
el.data('mousePressed', false);
el.bind('mousedown', function() {
jQuery(this).data('mousePressed', true);
});
jQuery(document).bind('mouseup', function() {
el.data('mousePressed', false);
});
el.bind('mousemove', jQuery.event.special.drag.handler);
},
// invoked when all drag events are removed from element
teardown: function(namespaces) {
var el = jQuery(this);
jQuery.removeData(this, 'mousePressed');
el.unbind('mousedown');
el.unbind('mouseup');
},
// our wrapper event is bound to "mousemove" and not "bind"
// change event type, so all attached drag handlers are fired
handler: function(event) {
event.type = 'drag';
jQuery.event.handle.apply(this, arguments);
}
};
Try something like this?
var isDown = false;
$(sel).mousedown(function() {
isDown = true;
});
$(sel).mouseup(function() {
isDown = false;
});
$(sel).mousemove(function() {
if (isDown) {
// Mouse is clicked and is moving.
}
});
If I'm reading your question correctly, you're asking about requiring the combination of multiple events to trigger a single function. It's possible to achieve this sort of thing, but I think it will depend greatly on the specific events and the logic or illogic of their combination. For example, the mousemove event:
...is triggered whenever the mouse
pointer moves, even for a pixel. This
means that hundreds of events can be
generated over a very small amount of
time.
Contrast that with the mousedown event, which is -- well, one per click. How to combine? The jQuery API goes on to state:
A common pattern is to bind the
mousemove handler from within a
mousedown hander [sic], and to unbind it
from a corresponding mouseup handler.
If implementing this sequence of
events, remember that the mouseup
event might be sent to a different
HTML element than the mousemove event
was. To account for this, the mouseup
handler should typically be bound to
an element high up in the DOM tree,
such as <body>.
Perhaps another approach would be to create a primitive finite state machine to ingest as inputs the various relevant events you have in mind, update its state accordingly, and then trigger a custom event when appropriate states are achieved. This all smells a little bit like reinventing the wheel, but maybe your requirement is very specific or unusual.
References: jQuery API: mousemove()
Alright, thanks for your idea Patrick. It reminded of a way I had done something like this in Java.
var m_down = false;
$(this).mousedown(function() {
m_down = true;
});
$(this).mouseup(function() {
m_down = false;
});
$(this).mousemove(function() {
// Code to occur here
});

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