Binding a function that is already bound to another element - javascript

I have a bunch of elements that get three different classes: neutral, markedV and markedX. When a user clicks one of these elements, the classes toggle once: neutral -> markedV -> markedX -> neutral. Every click will switch the class and execute a function.
$(document).ready(function(){
$(".neutral").click(function markV(event) {
alert("Good!");
$(this).addClass("markedV").removeClass("neutral");
$(this).unbind("click");
$(this).click(markX(event));
});
$(".markedV").click(function markX(event) {
alert("Bad!");
$(this).addClass("markedX").removeClass("markedV");
$(this).unbind("click");
$(this).click(neutral(event));
});
$(".markedX").click(function neutral(event) {
alert("Ok!");
$(this).addClass("neutral").removeClass("markedX");
$(this).unbind("click");
$(this).click(markV(event));
});
});
But obviously this doesn't work. I think I have three obstacles:
How to properly bind the changing element to the already defined function, sometimes before it's actually defined?
How to make sure to pass the event to the newly bound function [I guess it's NOT accomplished by sending 'event' to the function like in markX(event)]
The whole thing looks repetitive, the only thing that's changing is the alert action (Though each function will act differently, not necessarily alert). Is there a more elegant solution to this?

There's no need to constantly bind and unbind the event handler.
You should have one handler for all these options:
$(document).ready(function() {
var classes = ['neutral', 'markedV', 'markedX'],
methods = {
neutral: function (e) { alert('Good!') },
markedV: function (e) { alert('Bad!') },
markedX: function (e) { alert('Ok!') },
};
$( '.' + classes.join(',.') ).click(function (e) {
var $this = $(this);
$.each(classes, function (i, v) {
if ( $this.hasClass(v) ) {
methods[v].call(this, e);
$this.removeClass(v).addClass( classes[i + 1] || classes[0] );
return false;
}
});
});
});
Here's the fiddle: http://jsfiddle.net/m3CyX/

For such cases you need to attach the event to a higher parent and Delegate the event .
Remember that events are attached to the Elements and not to the classes.
Try this approach
$(document).ready(function () {
$(document).on('click', function (e) {
var $target = e.target;
if ($target.hasClass('markedV')) {
alert("Good!");
$target.addClass("markedV").removeClass("neutral");
} else if ($target.hasClass('markedV')) {
alert("Bad!");
$target.addClass("markedX").removeClass("markedV");
} else if ($target.hasClass('markedX')) {
alert("Ok!");
$target.addClass("neutral").removeClass("markedX");
}
});
});
OR as #Bergi Suggested
$(document).ready(function () {
$(document).on('click', 'markedV',function (e) {
alert("Good!");
$(this).addClass("markedV").removeClass("neutral");
});
$(document).on('click', 'markedX',function (e) {
alert("Bad!");
$(this).addClass("markedX").removeClass("markedV");
});
$(document).on('click', 'neutral',function (e) {
alert("Ok!");
$(this).addClass("neutral").removeClass("markedX");
});
});
Here document can be replaced with any static parent container..

How to properly bind the changing element to the already defined function, sometimes before it's actually defined?
You don't bind elements to functions, you bind handler functions to events on elements. You can't use a function before it is defined (yet you might use a function above the location in the code where it was declared - called "hoisting").
How to make sure to pass the event to the newly bound function [I guess it's NOT accomplished by sending 'event' to the function like in markX(event)]
That is what happens implicitly when the handler is called. You only need to pass the function - do not call it! Yet your problem is that you cannot access the named function expressions from outside.
The whole thing looks repetitive, the only thing that's changing is the alert action (Though each function will act differently, not necessarily alert). Is there a more elegant solution to this?
Yes. Use only one handler, and decide dynamically what to do in the current state. Do not steadily bind and unbind handlers. Or use event delegation.

Related

Binding multiple event handler pairs on dynamically generated elements in jquery with on

I have some dynamically generated elements with the class my-class on which I want to bind some events. I have the below code which works properly.
$(document).on("event1", ".my-class", function () {
alert("Event 1");
});
$(document).on("event2", ".my-class", function () {
alert("Event 2");
});
I want to refactor it so that there can be a single call to on for the category. Something like this
$(document).on(".my-class", {
"event1": function() {alert("Event1")},
"event2": function() {alert("Event2")}
});
Is this possible in jquery?
There might be a better way, but I've used this before and it worked for me:
Demo Fiddle
I wouldn't delegate off the document, instead I'd use the closest parent container.
JS:
$('body').on('click mouseenter', 'div', function(e) {
if (e.type === 'click') {
$('div').html('clicked');
}
else { //you'd need an else if here if you had more than two event types
$('div').html('mouse enter');
}
});

Best way to catch mouseup outside of mousedown element

$('#clickableElement').bind({
mousedown: function(e)
{
console.log('mousedown on element');
$(document).bind('mouseup',function(e){
console.log('mouseup caught');
//Do some magic here
$(this).unbind('mouseup');
});
},
mouseup:function(e)
{
//mouseup within element, no use here.
}
});
I'm trying to catch the mouseup event from a mousedown that's released inside or outside of an element. This code almost works, but the problem is the unbind('mouseup') which is unbinding other scripts attached to the mouseup event (jqueryui). If unbind() is not set then the code gets stacked within mouseup event and called x number of times, where x is the times you've mousedowned.
Route 1: is there some kind of self destructing function that calls itself once and destroys?
Route 2: any way to copy/clone the mouseup function prior to inserting the code, then unbind, then set as previous?
Ideally I'd like to keep this code structure for neatness as I have lots of clickable elements, so binding the document.mouseup outside of element.mousedown would be messy.
Here's the Fiddle I forgot to add http://jsfiddle.net/9gFNk/
Can giv your click event a namespace so only that namespaced event gets unbound, and not any others
$(document).on('mouseup.clickableElement',function(e){
console.log('mouseup caught');
//Do some magic here
$(this).off('mouseup.clickableElement');
});
I created a global object to catch mouse events from the document. It's currently set for mouseup only but can be easily expanded for others. The mouseup code is still customizable within the mousedown functions of the clickable elements so it this handy if you have lots of clickable things like I do.
var MouseCatcher=function()
{
this.init=function()
{
var mc = this;
$(document).bind({
mouseup:function(e)
{
mc.mouseup();
}
});
}
this.mouseup=function()
{
return false;
}
}
var mouseCatcher = new MouseCatcher();
mouseCatcher.init();
$('#clickableElement').bind({
mousedown: function(e)
{
console.log('mousedown on element');
mouseCatcher.mouseup=function()
{
console.log('mouseup called from MouseCatcher');
this.mouseup = function(){return false;}
}
},
mouseup:function(e)
{
//mouseup within element, no use here.
}
});
With "on" event its possible, its may not be an exact solution. Please refer this code
$(document).on('mousedown', function() {
$('#clickableElement').css('display', 'none');
$(document).bind('mouseup', function() {
$('#clickableElement').css('display', 'block');
});
});
http://jsfiddle.net/9gFNk/13/

JavaScript - Hook in some check on all 'click' events

So I have a regular onclick event attached to a few buttons, each function that handles the onclick event does something different (so I can't reuse the same function for both events).
element1.onclick = function() {
if(this.classList.contains('disabled') {
return false;
}
// For example make an AJAX call
};
element2.onclick = function() {
if(this.classList.contains('disabled') {
return false;
}
// For example hide a div
};
I'm writing duplicate code for this 'disabled' class check, I want to eliminate this by hooking in some common onclick check then fire the regular onclick event if that check passes.
I know the below won't work but I think it will illustrate what I'm trying to do:
document.addEventListener('click', function() {
// 1. Do the disabled check here
// 2. If the check passes delegate the event to the proper element it was invoked on
// 3. Otherwise kill the event here
});
I'm not using any JavaScript library and I don't plan to, in case someone comes up with 'Just use jQuery' type answers.
EDIT: Had to pass boolean third argument to addEventListener as true and everything is fine.
Use event capturing, like so:
document.addEventListener('click', function(event) {
if (/* your disabled check here */) {
// Kill the event
event.preventDefault();
event.stopPropagation();
}
// Doing nothing in this method lets the event proceed as normal
},
true // Enable event capturing!
);
Sounds like you need to set the capture flag to true and then use .stopPropagation() on the event if a certain condition is met at the target, f.ex:
document.addEventListener('click', function(e) {
if ( condition ) {
e.stopPropagation();
// do soemthing else, the default onclick will never happen
}
}, true);​​​​​​​​​​​​​​​​​​​​​​
Here is a demo: http://jsfiddle.net/v9TEj/
You can create a generic function that receives a callback:
//check everything here
function handleOnclick(callback) {
if(this.classList.contains("disabled")) {
return false;
} else {
callback(); //callback here
}
}
//and now on every onclick, just pass the custom behavior
element1.onclick = function() {
handleOnClick(function() {
console.log('element1 onclick fire'); // For example hide a div
});
};
element2.onclick = function() {
handleOnClick(function() {
console.log('element2 onclick fire'); // For example ajax request
});
};
Edit
Based on your latest comment, let me know if this rewrite works for you... only one biding this time.
element1.customFunction = function() {
handleOnClick(function() {
console.log('element1 onclick fire'); // For example hide a div
});
};
element2.customFunction = function() {
handleOnClick(function() {
console.log('element2 onclick fire'); // For example ajax request
});
};
document.addEventListener('click', function() {
//1. grab the element
//2. check if it has the customFunction defined
//3. if it does, call it, the check will be done inside
};

Toggling Classes Voids the Event function?

I thought this would work, but whenever I click on the element with the class name of one and it changes to the class named two, I can't get the second event to work. What am I missing here?
//first event
$('.one').on('click', function () {
$('.one').attr('class', 'two');
});
//second event
$('.two').on('click', function () {
$('.two').attr('class', 'one');
});
You need to delegate the event to a static parent..
The problem is , because you seem to dynamically change the class you need to bind the event every single time you change the class.. So delegating it should remove this problem..
Also You can write this as a Single event..
$('body').on('click','.one' , '.two', function() {
if( $(this).hasClass('one'){
function1();
}
else if( $(this).hasClass('two'){
function2();
}
$(this).toggleClass('one two');
});
Why not more simple :) http://jsfiddle.net/XZeNE/1/ or this http://jsfiddle.net/4mJJe/
use API - toggleClass
Further HTML CHange Dmeo http://jsfiddle.net/vuLQK/1/
code
$('.one').on('click', function() {
$(this).toggleClass('two');
});​
HTML change
$('.one').on('click', function() {
$(this).toggleClass(function(){
if($(this).hasClass('two'))
$(this).html('NOw its class two HTML HULK');
else
$(this).html('CLASS ONE HTML IRONMAN' );
return "two";
})
});
​
You should use .on to attach to one of the ancestors of the 2 elements and then use the selector argument to match the event target. The selectors won't match elements that aren't present when the handlers are bound.
$(function () {
$("#container").delegate(".one", "click", function () {
$(this).attr('class', 'two');
});
$("#container").delegate(".two", "click", function () {
$(this).attr('class', 'one');
});
})

How to write onshow event using JavaScript/jQuery?

I have an anchor tag on my page, I want an event attached to it, which will fire when the display of this element change.
How can I write this event, and catch whenever the display of this element changes?
This is my way of doing on onShow, as a jQuery plugin. It may or may not perform exactly what you are doing, however.
(function($){
$.fn.extend({
onShow: function(callback, unbind){
return this.each(function(){
var _this = this;
var bindopt = (unbind==undefined)?true:unbind;
if($.isFunction(callback)){
if($(_this).is(':hidden')){
var checkVis = function(){
if($(_this).is(':visible')){
callback.call(_this);
if(bindopt){
$('body').unbind('click keyup keydown', checkVis);
}
}
}
$('body').bind('click keyup keydown', checkVis);
}
else{
callback.call(_this);
}
}
});
}
});
})(jQuery);
You can call this inside the $(document).ready() function and use a callback to fire when the element is shown, as so.
$(document).ready(function(){
$('#myelement').onShow(function(){
alert('this element is now shown');
});
});
It works by binding a click, keyup, and keydown event to the body to check if the element is shown, because these events are most likely to cause an element to be shown and are very frequently performed by the user. This may not be extremely elegant but gets the job done. Also, once the element is shown, these events are unbinded from the body as to not keep firing and slowing down performance.
You can't get an onshow event directly in JavaScript. Do remember that the following methods are non-standard.
IN IE you can use
onpropertychange event
Fires after the property of an element
changes
and for Mozilla
you can use
watch
Watches for a property to be assigned
a value and runs a function when that
occurs.
You could also override jQuery's default show method:
var orgShow = $.fn.show;
$.fn.show = function()
{
$(this).trigger( 'myOnShowEvent' );
orgShow.apply( this, arguments );
return this;
}
Now just bind your code to the event:
$('#foo').bind( "myOnShowEvent", function()
{
console.log( "SHOWN!" )
});
The code from this link worked for me: http://viralpatel.net/blogs/jquery-trigger-custom-event-show-hide-element/
(function ($) {
$.each(['show', 'hide'], function (i, ev) {
var el = $.fn[ev];
$.fn[ev] = function () {
this.trigger(ev);
return el.apply(this, arguments);
};
});
})(jQuery);
$('#foo').on('show', function() {
console.log('#foo is now visible');
});
$('#foo').on('hide', function() {
console.log('#foo is hidden');
});
However the callback function gets called first and then the element is shown/hidden. So if you have some operation related to the same selector and it needs to be done after being shown or hidden, the temporary fix is to add a timeout for few milliseconds.

Categories