I am trying to iterate over the following Code and for some reason each time i iterate over it, it fires off the event handler, does any one know why it would be automatically firing off the handler?
nmbr = 1;
x1 = document.getElementsByClassName('fp')[0] ;
slowSkrol = document.createElement('button');
slowSkrol.className = 'mods';
slowSkrol.value= nmbr;
x1.appendChild(slowSkrol);
slowSkrol.addEventListener('click', whenclicked(nmbr),false);
function whenclicked(vv){
alert(vv);
}
You are calling the function, and binding it's return value to the event, rather than binding the function itself to the event. Replace whenclicked(nmbr) with:
function(){ whenclicked(nmbr); }
In modern browsers you could also use bind:
whenclicked.bind(null, nmbr);
change:
slowSkrol.addEventListener('click', whenclicked(nmbr),false);
to
slowSkrol.addEventListener('click', function() {
whenclicked(nmbr);
},false);
I shouldn't be adding another answer really. but the correct way to do this so that you get all arguments and the this would be like so.
slowSkrol.addEventListener('click', function( event ) {
whenclicked.apply(this, [event, nmbr]);
}, false);
Then you can use it like so.
function whenclicked( event, nmbr ){
alert(this, event, nmbr);
// this = slowSkrol
}
Related
p.num = 100;
$('body').on('click', '.del', this.delete.bind(this));
p.delete = function(e) {
console.log(this.num); //100
//how can I get the .del element?
}
I'm trying to get the element that produced the click, but I also need access to the num property.
How can I access both types of 'this' inside my delete method?
The callback for an event receives an Event object that you can use to retrieve the element on which the event was called.
function(e) {
var element = $(e.target); //This is the element that the event was called on.
}
Disclaimer : This is the my exact answer (adapted with the current code) taken from here : Pass additional arguments to event handler?
Yet, the question doesn't seem to be an exact duplicate (but i may be wrong).
As said in the documentation of .on, you can pass datas to your event.
.on( events [, selector ] [, data ], handler )
data
Type: Anything
Data to be passed to the handler in event.data when an event is triggered.
So your event could look like that :
p.num = 100;
$('body').on('click', '.del', {object : this}, this.delete);
p.delete = function(e) {
var myObj = e.data.object;
// [myObj] will be your plugin
// [this] will be the clicked element
// [e] will be you event
}
if you're using jquery, you can combine those functions all into one like below:
note: num is an attribute so you have to use .attr().
$(document).ready(function() {
$('body').on('click', '.del', function() {
var num = $(this).attr('num');
alert('click function and num = ' + num);
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
Delete
or if you really want to keep them separate functions....:
$(document).ready(function() {
$('.del').on('click', function() {
deleteThis($(this));
});
});
function deleteThis(element){
var num = element.attr('num');
alert('click function and num = ' + num);
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
Delete
also, if youre using separate functions for the click and the delete, pass the element from click to delete: pass element - callDeleteFunction($(this)), and retrieve element - myDeleteFunction(element aka $(this))
I'm not sure what you're asking about but maybe this is what you want:
var p = {};
p.num = 100;
$('body').on('click', '.del', p.delete); // don't bind to this
p.delete = function(e) {
console.log(p.num); // here you still can call p
// this is del DOM element
}
I want to create a function and then use with onclick method, for example:
one = document.getElementById("oneID");
then instead of writing function for each onclick():
one.onclick = function(x) {
tempStack.push(parseFloat(one.value));
viewTemp.value += one.value;
}
I want to use a single function:
one.click = input(one);
but I'm not sure how to do it in the correct way for example the below I tried, doesn't work:
var input = function(x) {
tempStack.push(parseFloat(x.value));
viewTemp.value += x.value;
}
Lastly, no external JavaScript libraries to aid this question, vanilla JavaScript.
You'll need to pass a function as a reference, not call it:
one.onclick = input;
In this case you won't be able to pass an argument, but you can use this as a reference for the DOM element on which event is fired:
function input() {
tempStack.push(parseFloat(this.value));
viewTemp.value += this.value;
}
Here's a method with using JavaScript's .addEventListener(), as a previous answer mentioned, using this to pass through the DOM Node Element to use within the inputFunction.
<input type="text" value="64.23" id="bt" />
<script>
function inputFunction( x ) {
console.log( x.value ); //Console Logs 64.23
}
var bt = document.getElementById("bt");
bt.addEventListener( 'click', function(){ inputFunction( this )}, false );
</script>
Fiddle: http://jsfiddle.net/Lhq6t/
Think about functions as a normal objects, so the way is:
function input (event) {
// Process the event...
// event is my event object
// this is the object which trigger the event
// event.target is my button
}
on.onclick = input;
You must assign the input function as a normal variable.
The function input will receive an event object as parameter. Also you can refer to the button clicked with this.
Maybe the mozilla developer network or the real w3c site would explain it better.
Your requirement can be achieved by following:
Add this method in your script tag:
function input(x) {
/*tempStack.push(parseFloat(x.value));
viewTemp.value += x.value;*/
alert(x.id);
}
And then call this method onClick event of your buttons / anchors like:
<input type="button" id="oneID" value="oneID" onClick="input(this);"/>
<input type="button" id="twoID" value="twoID" onClick="input(this);"/>
threeID
See working example: http://jsfiddle.net/Avd5U/1/
ok, so just create a function with a parameter in it like:
function setValue(input){
tempStack.push(parseFloat(input.value));
viewTemp.value += input.value;
}
and then call the function on the click of that element like:
var one = document.getElementById("oneID");
one.click = setValue(one);
Good luck!
I am looking for a way to manage the events. I have a hover function for element A, and click function for element B. I want to disable A`s hover function temporary while the second click of B.
I am looking for a way that not necessary to rewrite the hole function of A inside of B. Something very simply just like "Store and Disable Event, Call Stored Function"
I found some technique like .data('events') and console.log. I tired but failed, or maybe I wrote them in a wrong way.
Please help and advice!
$(A).hover();
$(b).click(
if($.hasData($(A)[0])){ // if A has event,
//STORE all the event A has, and disable
}else{
//ENABLE the stored event for A
}
);
Try this
var hoverme = function() {
alert('Hover Event Fired');
};
$('.A').hover(hoverme);
var i = 0;
$('.B').on('click', function(){
if(i%2 === 0){
// Unbind event
$('.A').off('hover');
}
else{
// Else bind the event
$('.A').hover(hoverme);
}
i++;
});
Check Fiddle
I think that what you want to do is something like this (example for JQuery 1.7.2):
$("#a").hover(function(){alert("test")});
$("#a")[0].active=true;
$("#b").click(function(){
if($("#a")[0].active){
$("#a")[0].storedEvents = [];
var hoverEvents = $("#a").data("events").mouseover;
jQuery.each(hoverEvents , function(key,handlerObj) {
$("#a")[0].storedEvents.push(handlerObj.handler);
});
$("#a").off('hover');
}else{
for(var i=0;i<$("#a")[0].storedEvents.length;i++){
$("#a").hover($("#a")[0].storedEvents[i]);
}
}
$("#a")[0].active = ($("#a")[0].active)==false;
});
JSFiddle Example
But there are a couple of things that you must have in consideration:
This will only work if you add the events with JQuery, because JQuery keeps an internal track of the event handlers that have been added.
Each version of JQuery handles data("events") differently, that means that this code may not work with other version of JQuery.
I hope that this helps.
EDIT:
data("events") was an internal undocumented data structure used in JQuery 1.6 and JQUery 1.7, but it has been removed in JQuery 1.8. So in JQuery 1.8 the only way to access the events data is through: $._data(element, "events"). But keep in mind the advice from the JQuery documentation: this is not a supported public interface; the actual data structures may change incompatibly from version to version.
You could try having a variable that is outside the scope of functions a and b, and use that variable to trigger the action to take in function b on function a.
var state;
var a = function() {
if(!state) {
state = true;
// Add hover action and other prep. I'd create a third function to handle this.
console.log(state);
};
var b = function() {
if(state) {
state = false;
// Do unbinding of hover code with third function.
} else {
state = true;
// Do whatever else you needed to do
}
}
Without knowing more about what you're trying to do, I'd try something similar to this.
It sounds like you want to disable the click hover event for A if B is clicked.
$("body").on("hover", "#a", function(){
alert("hovering");
});
$("#b").click( function(){
$("body").off("hover", "#a", function() {
alert("removed hovering");
});
});
You can use the jQuery off method, have a look at this fiddle. http://jsfiddle.net/nKLwK/1/
Define a function to assign to hover on A element, so in b click, call unbind('hover') for A element and in second click on b element define again a function to hover, like this:
function aHover(eventObject) {
// Todo when the mouse enter object. You can use $(this) here
}
function aHoverOut(eventObject) {
// Todo when the mouse leave the object. You can use $(this) here
}
$(A).hover(aHover, aHoverOut);
// ...
$(b).click(function(eventObject) {
if($.hasData($(A)[0])){ // if A has event,
$(A).unbind('mouseenter mouseleave'); // This is because not a event hover, jQuery convert the element.hover(hoverIn, hoverOut) in element.bind('mouseenter', hoverIn) and element.bind('mouseleave', hoverOut)
}else{
$(A).hover(aHover, aHoverOut);
}
});
There are provably better ways to do it, but this works fine, on document ready do this:
$("#a")[0].active=false;
$("#b").click(function(){
$("#a")[0].active = ($("#a")[0].active)==false;
if($("#a")[0].active){
$("#a").hover(function(){alert("test")});
}else{
$("#a").off('hover');
}
});
JSFiddle example
You can use .off function from jQuery to unbind the hover on your "a" element.
function hoverA() {
alert('I\'m on hover');
}
$('#a').hover( hoverA );
var active = true;
$('#b').on('click', function(){
if(active){
$('#a').off('hover');
active = false;
} else{
$('#a').hover(hoverA);
active = true;
}
});
Live demo available here : http://codepen.io/joe/pen/wblpC
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!");
$(this).addClass("neutral").removeClass("markedX");
});
});
Here document can be replaced with any static parent container..
How to properly bind the changing element to the already defined function, sometimes before it's actually defined?
You don't bind elements to functions, you bind handler functions to events on elements. You can't use a function before it is defined (yet you might use a function above the location in the code where it was declared - called "hoisting").
How to make sure to pass the event to the newly bound function [I guess it's NOT accomplished by sending 'event' to the function like in markX(event)]
That is what happens implicitly when the handler is called. You only need to pass the function - do not call it! Yet your problem is that you cannot access the named function expressions from outside.
The whole thing looks repetitive, the only thing that's changing is the alert action (Though each function will act differently, not necessarily alert). Is there a more elegant solution to this?
Yes. Use only one handler, and decide dynamically what to do in the current state. Do not steadily bind and unbind handlers. Or use event delegation.
I have an anchor tag on my page, I want an event attached to it, which will fire when the display of this element change.
How can I write this event, and catch whenever the display of this element changes?
This is my way of doing on onShow, as a jQuery plugin. It may or may not perform exactly what you are doing, however.
(function($){
$.fn.extend({
onShow: function(callback, unbind){
return this.each(function(){
var _this = this;
var bindopt = (unbind==undefined)?true:unbind;
if($.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.