I have a code like this:
function myfunc () {
alert('executed');
}
$('.classname').on('click' function () {
myfunc();
});
I want to run myfunc once. I mean I don't want to execute it every time when user clicks on .classname element. I guess I need to warp function-calling into a condition. Something like this:
if ( /* that function never executed so far */ ) {
myfunc();
}
How can I do that?
The simplest way with jQuery is to use .one
function myfunc() {
alert('executed');
}
$('.classname').one('click', function() {
myfunc();
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<button class="classname">click here!</button>
You should remove the event listener in the function you're calling:
function myfunc () {
alert('executed');
$('.classname').off('click', myfunc);
}
$('.classname').on('click', myfunc);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class='classname'>Click Me</div>
Don't set a global variable like the other posts describe - there's no need for that and then you're still doing an unnecessary function call. This ensures the function is never called again and the event isn't being listed for.
$( document ).ready(function() {
var hasBeenExecuted = false;
function myfunc () {
alert('executed');
hasBeenExecuted = true;
}
$('.classname').on('click' function () {
if(!hasBeenExecuted){
myfunc();
}
});
});
var functionWasRun = false;
function myfunc () {
functionWasRun = true;
alert('executed');
}
$(document).ready(function() {
$('.classname').on('click', function () {
if (!functionWasRun) {
myfunc();
}
});
});
I would suggest, as an alternative to a global variable, assigning a property to the function.
function myfunc () {
alert('executed');
myfunc.executed = true;
}
$('.classname').on('click', function () {
if(!myfunc.executed) {
myfunc();
}
});
This has the advantage of working the same way while not polluting the global scope unnecessarily. However, if skyline3000's answer works for you, you should use that instead as it's cleaner and more sensible overall.
How do I run a function only once? I read about jquery .one but it seems to only work with click functions. I need my audio play function to activate only once otherwise I have two audio players when the user clicks on the same link again.
How would I do this? Here is piece of code I need running once:
$(function() {
$('audio').audioPlayer();
});
and here the full code:
$('ul li:nth-child(2)').click(function(e) {;
e.preventDefault();
link1.reverse()
link2.reverse()
link3.reverse()
$('#div').uncomment( /* recurse */ true);
setTimeout(function() {
link4.play()
$(function() {
$('audio').audioPlayer();
});
picturefill({
reevaluate: true
});
},
You could simply use a variable to track whether or not it has been executed. And you don't need the $(function() {...} inside the setTimeout function as this binding is already going to be created after the DOM is ready.
E.g.
HTML:
<ul>
<li>test</li>
<li>click me</li>
<li>test</li>
</ul>
JS:
var hasPlayed = false;
$(function () {
$('ul li:nth-child(2)').click(function (e) {;
e.preventDefault();
link1.reverse();
link2.reverse();
link3.reverse();
$('#div').uncomment( /* recurse */ true);
if (!hasPlayed) {
hasPlayed = true;
setTimeout(function () {
link4.play();
$('audio').audioPlayer();
picturefill({
reevaluate: true
});
}, 1000);
}
});
});
Fiddle: http://jsfiddle.net/BenjaminRay/2eaf28jh/
Try using data attributes,
var playAudio = function() {
if ($('.audio').data('once') != true) {
$('.audio').append('Once'); // replace with $('audio').audioPlayer();
$('.audio').data('once', true)
}
};
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<div class="audio"></div>
Click Me
You could use a guard condition. I'm not that familiar with this audioPlayer(), but if there is a way to ask "is it playing" you could do
if (!audioPlayer.isPlaying()) {
$('audio').audioPlayer();
}
Otherwise you could do something like
//Outside the click handler
var isFirstRun = true;
...
//Inside the click handler
if (isFirstRun) {
isFirstRun = false;
$('audio').audioPlayer();
}
I want to call a function with a namespace based on its name.
Perhaps some background: What I want is, dynamically bind pages via $.mobile.loadPage(inStrUrl, { showLoadMsg: false }); and then, based on the current page, invoke a function within a loaded page. For example: each page has a showFilter function, the Event is attached to a main.html - page which should call the matching function in the current page.
I also tried some solutions, with jquery too, but nothing works for me.
This is my function code:
function namespace() { }
namespace.showFilter = function () {
alert("Test");
}
And want to "invoke" or "call" it via its name.
This is what i tried at least.
$(document).ready(function() {
var fn = window["namespace.showFilter"];
fn();
});
I get error TypeError: fn is not a function
Here is a fiddle http://jsfiddle.net/xBCes/1/
You can call it in the following way:
$(document).ready(function() {
window["namespace"]["showFilter"]();
});
or
$(document).ready(function() {
window["namespace"].showFilter();
});
or
$(document).ready(function() {
window.namespace.showFilter();
});
I found that I had to manually set it to window.
window.namespace = function() { }
window.namespace.showFilter = function () {
alert("Test");
};
$(document).ready(function() {
var fn = window["namespace"]["showFilter"];
fn();
});
http://jsfiddle.net/xBCes/4/
Like this:
$(function() {
window.namespace.showFilter();
});
P.S. I shortened the $(document).ready(...)
function namespace() {}
namespace.showFilter = function () {
alert("Test");
}
$(document).ready(function() {
var fn = namespace.showFilter();
fn();
});
http://jsfiddle.net/xBCes/3/
I am stuck. Searched and tried for hours.
EDIT:
I still can't make it work. Okay, I'll just put the source code to make it clear what I want to accomplish.
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.min.js"></script>
<script type="text/javascript">
var date_fmt="yyyy-mm-dd";
var time_fmt="HH:MM";
var date_field="#id_start_0, #id_end_0"; //id refering to html input type='text'
var time_field="#id_start_1, #id_end_1"; //id refereing to html input type='text'
function clearFmt(fmt_type)
{
if($(this).val() == fmt_type) {
$(this).val("");
}
}
function putFmt(fmt_type)
{
if($(this).val() == "") {
$(this).val(fmt_type);
}
}
$(document).ready(function() {
$(date_field).attr("title",date_fmt);
$(time_field).attr("title",time_fmt);
$(date_field).click(function() {
clearFmt(date_fmt);
});
$(date_field).blur(function(){
putFmt(date_fmt);
});
$(time_field).click(function(){
clearFmt(time_fmt);
});
$(time_field).blur(function(){
putFmt(time_fmt);
});
});
</script>
Help ?
Use the jquery bind method:
function myfunc(param) {
alert(param.data.key);
}
$(document).ready( function() {
$("#foo").bind('click', { key: 'value' }, myfunc);
});
Also see my jsfiddle.
=== UPDATE ===
since jquery 1.4.3 you also can use:
function myfunc(param) {
alert(param.data.key);
}
$(document).ready( function() {
$("#foo").click({ key: 'value' }, myfunc);
});
Also see my second jsfiddle.
=== UPDATE 2 ===
Each function has his own this. After calling clearFmt in this function this is no longer the clicked element. I have two similar solutions:
In your functions add a parameter called e.g. element and replace $(this) with element.
function clearFmt(element, fmt_type) {
if (element.val() == fmt_type) {
element.val("");
}
}
Calling the function you have to add the parameter $(this).
$(date_field).click(function() {
clearFmt($(this), date_fmt);
});
Also see my third jsfiddle.
-=-
An alternative:
function clearFmt(o) {
if ($(o.currentTarget).val() == o.data.fmt_type) {
$(o.currentTarget).val("");
}
}
$(date_field).click({fmt_type: date_fmt}, clearFmt);
Also see my fourth jsfiddle.
The following should work as seen in this live demo:
function myfunc(bar) {
alert(bar);
}
$(function() {
$("#foo").click( function() {
myfunc("value");
});
});
anyFunctionName = (function()
{
function yourFunctionName1()
{
//your code here
}
function yourFunctionName2(parameter1, param2)
{
//your code here
}
return
{
yourFunctionName1:yourFunctionName1,
yourFunctionName2:yourFunctionName2
}
})();
$document.ready(function()
{
anyFunctionName.yourFunctionName1();
anyFunctionName.yourFunctionName2();
});
Note: if you don't use 'anyFuctionName' to declare any function then no need return method. just write your function simply like, yourFunctionName1().
in $document.ready section parameter is not issue. you just put your function name here. if you use 'anyFuctionName' function then you have to follow above format.
function myfunc(e) {
alert(e.data.bar); //this is set to "value"
}
$("#foo").click({bar: "value"}, myfunc);
People are making this complicated, simply call directly as you would in Javascript
myfunc("value");
I'm using jQuery in my site and I would like to trigger certain actions when a certain div is made visible.
Is it possible to attach some sort of "isvisible" event handler to arbitrary divs and have certain code run when they the div is made visible?
I would like something like the following pseudocode:
$(function() {
$('#contentDiv').isvisible(function() {
alert("do something");
});
});
The alert("do something") code should not fire until the contentDiv is actually made visible.
Thanks.
You could always add to the original .show() method so you don't have to trigger events every time you show something or if you need it to work with legacy code:
Jquery extension:
jQuery(function($) {
var _oldShow = $.fn.show;
$.fn.show = function(speed, oldCallback) {
return $(this).each(function() {
var obj = $(this),
newCallback = function() {
if ($.isFunction(oldCallback)) {
oldCallback.apply(obj);
}
obj.trigger('afterShow');
};
// you can trigger a before show if you want
obj.trigger('beforeShow');
// now use the old function to show the element passing the new callback
_oldShow.apply(obj, [speed, newCallback]);
});
}
});
Usage example:
jQuery(function($) {
$('#test')
.bind('beforeShow', function() {
alert('beforeShow');
})
.bind('afterShow', function() {
alert('afterShow');
})
.show(1000, function() {
alert('in show callback');
})
.show();
});
This effectively lets you do something beforeShow and afterShow while still executing the normal behavior of the original .show() method.
You could also create another method so you don't have to override the original .show() method.
The problem is being addressed by DOM mutation observers. They allow you to bind an observer (a function) to events of changing content, text or attributes of dom elements.
With the release of IE11, all major browsers support this feature, check http://caniuse.com/mutationobserver
The example code is a follows:
$(function() {
$('#show').click(function() {
$('#testdiv').show();
});
var observer = new MutationObserver(function(mutations) {
alert('Attributes changed!');
});
var target = document.querySelector('#testdiv');
observer.observe(target, {
attributes: true
});
});
<div id="testdiv" style="display:none;">hidden</div>
<button id="show">Show hidden div</button>
<script type="text/javascript" src="https://code.jquery.com/jquery-1.9.1.min.js"></script>
There is no native event you can hook into for this however you can trigger an event from your script after you have made the div visible using the .trigger function
e.g
//declare event to run when div is visible
function isVisible(){
//do something
}
//hookup the event
$('#someDivId').bind('isVisible', isVisible);
//show div and trigger custom event in callback when div is visible
$('#someDivId').show('slow', function(){
$(this).trigger('isVisible');
});
You can use jQuery's Live Query plugin.
And write code as follows:
$('#contentDiv:visible').livequery(function() {
alert("do something");
});
Then everytime the contentDiv is visible, "do something" will be alerted!
redsquare's solution is the right answer.
But as an IN-THEORY solution you can write a function which is selecting the elements classed by .visibilityCheck (not all visible elements) and check their visibility property value; if true then do something.
Afterward, the function should be performed periodically using the setInterval() function. You can stop the timer using the clearInterval() upon successful call-out.
Here's an example:
function foo() {
$('.visibilityCheck').each(function() {
if ($(this).is(':visible')){
// do something
}
});
}
window.setInterval(foo, 100);
You can also perform some performance improvements on it, however, the solution is basically absurd to be used in action. So...
The following code (pulled from http://maximeparmentier.com/2012/11/06/bind-show-hide-events-with-jquery/) will enable you to use $('#someDiv').on('show', someFunc);.
(function ($) {
$.each(['show', 'hide'], function (i, ev) {
var el = $.fn[ev];
$.fn[ev] = function () {
this.trigger(ev);
return el.apply(this, arguments);
};
});
})(jQuery);
If you want to trigger the event on all elements (and child elements) that are actually made visible, by $.show, toggle, toggleClass, addClass, or removeClass:
$.each(["show", "toggle", "toggleClass", "addClass", "removeClass"], function(){
var _oldFn = $.fn[this];
$.fn[this] = function(){
var hidden = this.find(":hidden").add(this.filter(":hidden"));
var result = _oldFn.apply(this, arguments);
hidden.filter(":visible").each(function(){
$(this).triggerHandler("show"); //No bubbling
});
return result;
}
});
And now your element:
$("#myLazyUl").bind("show", function(){
alert(this);
});
You could add overrides to additional jQuery functions by adding them to the array at the top (like "attr")
a hide/show event trigger based on Glenns ideea:
removed toggle because it fires show/hide and we don't want 2fires for one event
$(function(){
$.each(["show","hide", "toggleClass", "addClass", "removeClass"], function(){
var _oldFn = $.fn[this];
$.fn[this] = function(){
var hidden = this.find(":hidden").add(this.filter(":hidden"));
var visible = this.find(":visible").add(this.filter(":visible"));
var result = _oldFn.apply(this, arguments);
hidden.filter(":visible").each(function(){
$(this).triggerHandler("show");
});
visible.filter(":hidden").each(function(){
$(this).triggerHandler("hide");
});
return result;
}
});
});
I had this same problem and created a jQuery plugin to solve it for our site.
https://github.com/shaunbowe/jquery.visibilityChanged
Here is how you would use it based on your example:
$('#contentDiv').visibilityChanged(function(element, visible) {
alert("do something");
});
What helped me here is recent ResizeObserver spec polyfill:
const divEl = $('#section60');
const ro = new ResizeObserver(() => {
if (divEl.is(':visible')) {
console.log("it's visible now!");
}
});
ro.observe(divEl[0]);
Note that it's crossbrowser and performant (no polling).
Just bind a trigger with the selector and put the code into the trigger event:
jQuery(function() {
jQuery("#contentDiv:hidden").show().trigger('show');
jQuery('#contentDiv').on('show', function() {
console.log('#contentDiv is now visible');
// your code here
});
});
Use jQuery Waypoints :
$('#contentDiv').waypoint(function() {
alert('do something');
});
Other examples on the site of jQuery Waypoints.
I did a simple setinterval function to achieve this. If element with class div1 is visible, it sets div2 to be visible. I know not a good method, but a simple fix.
setInterval(function(){
if($('.div1').is(':visible')){
$('.div2').show();
}
else {
$('.div2').hide();
}
}, 100);
You can also try jQuery appear plugin as mentioned in parallel thread https://stackoverflow.com/a/3535028/741782
This support easing and trigger event after animation done! [tested on jQuery 2.2.4]
(function ($) {
$.each(['show', 'hide', 'fadeOut', 'fadeIn'], function (i, ev) {
var el = $.fn[ev];
$.fn[ev] = function () {
var result = el.apply(this, arguments);
var _self=this;
result.promise().done(function () {
_self.triggerHandler(ev, [result]);
//console.log(_self);
});
return result;
};
});
})(jQuery);
Inspired By http://viralpatel.net/blogs/jquery-trigger-custom-event-show-hide-element/
There is a jQuery plugin available for watching change in DOM attributes,
https://github.com/darcyclarke/jQuery-Watch-Plugin
The plugin wraps All you need do is bind MutationObserver
You can then use it to watch the div using:
$("#selector").watch('css', function() {
console.log("Visibility: " + this.style.display == 'none'?'hidden':'shown'));
//or any random events
});
Hope this will do the job in simplest manner:
$("#myID").on('show').trigger('displayShow');
$('#myID').off('displayShow').on('displayShow', function(e) {
console.log('This event will be triggered when myID will be visible');
});
I changed the hide/show event trigger from Catalint based on Glenns idea.
My problem was that I have a modular application. I change between modules showing and hiding divs parents. Then when I hide a module and show another one, with his method I have a visible delay when I change between modules. I only need sometimes to liten this event, and in some special childs. So I decided to notify only the childs with the class "displayObserver"
$.each(["show", "hide", "toggleClass", "addClass", "removeClass"], function () {
var _oldFn = $.fn[this];
$.fn[this] = function () {
var hidden = this.find(".displayObserver:hidden").add(this.filter(":hidden"));
var visible = this.find(".displayObserver:visible").add(this.filter(":visible"));
var result = _oldFn.apply(this, arguments);
hidden.filter(":visible").each(function () {
$(this).triggerHandler("show");
});
visible.filter(":hidden").each(function () {
$(this).triggerHandler("hide");
});
return result;
}
});
Then when a child wants to listen for "show" or "hide" event I have to add him the class "displayObserver", and when It does not want to continue listen it, I remove him the class
bindDisplayEvent: function () {
$("#child1").addClass("displayObserver");
$("#child1").off("show", this.onParentShow);
$("#child1").on("show", this.onParentShow);
},
bindDisplayEvent: function () {
$("#child1").removeClass("displayObserver");
$("#child1").off("show", this.onParentShow);
},
I wish help
One way to do this.
Works only on visibility changes that are made by css class change, but can be extended to watch for attribute changes too.
var observer = new MutationObserver(function(mutations) {
var clone = $(mutations[0].target).clone();
clone.removeClass();
for(var i = 0; i < mutations.length; i++){
clone.addClass(mutations[i].oldValue);
}
$(document.body).append(clone);
var cloneVisibility = $(clone).is(":visible");
$(clone).remove();
if (cloneVisibility != $(mutations[0].target).is(":visible")){
var visibilityChangedEvent = document.createEvent('Event');
visibilityChangedEvent.initEvent('visibilityChanged', true, true);
mutations[0].target.dispatchEvent(visibilityChangedEvent);
}
});
var targets = $('.ui-collapsible-content');
$.each(targets, function(i,target){
target.addEventListener('visibilityChanged',VisbilityChanedEventHandler});
target.addEventListener('DOMNodeRemovedFromDocument',VisbilityChanedEventHandler });
observer.observe(target, { attributes: true, attributeFilter : ['class'], childList: false, attributeOldValue: true });
});
function VisbilityChanedEventHandler(e){console.log('Kaboom babe'); console.log(e.target); }
my solution:
; (function ($) {
$.each([ "toggle", "show", "hide" ], function( i, name ) {
var cssFn = $.fn[ name ];
$.fn[ name ] = function( speed, easing, callback ) {
if(speed == null || typeof speed === "boolean"){
var ret=cssFn.apply( this, arguments )
$.fn.triggerVisibleEvent.apply(this,arguments)
return ret
}else{
var that=this
var new_callback=function(){
callback.call(this)
$.fn.triggerVisibleEvent.apply(that,arguments)
}
var ret=this.animate( genFx( name, true ), speed, easing, new_callback )
return ret
}
};
});
$.fn.triggerVisibleEvent=function(){
this.each(function(){
if($(this).is(':visible')){
$(this).trigger('visible')
$(this).find('[data-trigger-visible-event]').triggerVisibleEvent()
}
})
}
})(jQuery);
example usage:
if(!$info_center.is(':visible')){
$info_center.attr('data-trigger-visible-event','true').one('visible',processMoreLessButton)
}else{
processMoreLessButton()
}
function processMoreLessButton(){
//some logic
}
$( window ).scroll(function(e,i) {
win_top = $( window ).scrollTop();
win_bottom = $( window ).height() + win_top;
//console.log( win_top,win_bottom );
$('.onvisible').each(function()
{
t = $(this).offset().top;
b = t + $(this).height();
if( t > win_top && b < win_bottom )
alert("do something");
});
});
$(function() {
$(document).click(function (){
if ($('#contentDiv').is(':visible')) {
alert("Visible");
} else {
alert("Hidden");
}
});
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="contentDiv">Test I'm here</div>
<button onclick="$('#contentDiv').toggle();">Toggle the div</button>
<div id="welcometo">Özhan</div>
<input type="button" name="ooo"
onclick="JavaScript:
if(document.all.welcometo.style.display=='none') {
document.all.welcometo.style.display='';
} else {
document.all.welcometo.style.display='none';
}">
This code auto control not required query visible or unvisible control