Callback not working properly - javascript

HTML
<div class="expand">
<span>▲</span>
</div>
JS
$(".expand").click(function(){
if ($(this).children().text()=="▼") {
$(this).children().fadeOut("fast",function(){
$(this).children().text("▲");
}); // callback?
$(this).children().fadeIn("fast"); //woks
} else {
$(this).children().fadeOut("fast",function(){
$(this).children().text("▼");
}); // callback?
$(this).children().fadeIn("fast"); //works
};
$(this).parent().parent().find(".words, .readings").slideToggle("fast"); //works
});
I tried debugging it by putting alert('') in callback, but nothing popped up, so I guess I'm making some simple mistake here. Basically, ▼ should fade out and when it fades out (callback), it should turn into ▲, and then fade in, like that. Pretty standard we seen everywhere if you ask me. Or I'm doing this completely wrong?
I'd prefer corrections on my implementation than completely different solutions, although they're welcome as well.

Inside of the callback, this is already the element you want, so $(this).children() returns an empty object because that <span> does not have children. Remove the .children() from the callback:
$(this).children().fadeOut("fast",function(){
$(this).text("▲");
});

Inside the callback $(this) is already the span that you are looking for. So just use $(this).text(), as $(this).children() will fetch nothing as there are no child elements for the span and it will eventually point to the wrong target event if it has children.
Also place your fadeIn() inside the callback, if outside it will get executed before the callback executes.
$(".expand").click(function () {
if ($(this).children().text() == "▼") {
$(this).children().fadeOut("fast", function () {
$(this).text("▲").fadeIn("fast");
}); // callback?
} else {
$(this).children().fadeOut("fast", function () {
$(this).text("▼").fadeIn("fast");
}); // callback?
};
$(this).parent().parent().find(".words, .readings").slideToggle("fast"); //works
});
Fiddle
You can just simplify this to:
$(".expand").click(function () {
$(this).children().fadeOut(function () {
$(this).text(function (_, val) {
return val == "▼" ? "▲" : "▼";
}).fadeIn("fast");
})
$(this).parent().parent().find(".words, .readings").slideToggle("fast"); //works
});
Fiddle

Related

jsViews $.observable(arr).insert() not triggering DOM update

I am using $.observable(array).insert() to append items to a list. This is updating my view as it should: new list items are rendered to the DOM. However, I would like to issue a click event on the new DOM node (I'm relying on the event to add a class to expand the item and attach another listener to the body so the area can be closed).
I have tried both
$.observable(_model.leadTimes).insert(leadTime);
$leadTimes.find('.lead-time-data').last().find('.start-editing').click();
...and
function watchLeadTimes() {
var changeHandler = function (ev, eventArgs) {
if (eventArgs.change === 'insert') {
$leadTimes.find('.lead-time-data').last().find('.start-editing').click();
}
};
$.observe(_model.leadTimes, changeHandler);
}
And neither of them worked, however, if I wrap the jQuery method in a setTimout, like setTimeout(function () { $leadTimes.find('.lead-time-data').last().find('.start-editing').click(); }, 400);, it does work, leading me to believe this is an issue of timing with the DOM render somehow not finishing before my jQuery click() method is invoked.
Since the odds are decent that you will see this, Borris, thank you for the library and all that you do! I think jsViews is an excellent middle ground between the monolithic frameworks out there and plain old jQuery noodling!
Edit 02/09/17
It turns out my issue was overlapping click events--I was inadvertently handling a click to deselect my element immediately after it was selected. However I took the opportunity to rewrite things to use a more declarative approach following Borris' linked example.
Now in my template I am using a computed observable, isSelected to toggle the .editing class:
{^{for leadTimes}}
<tr class="lead-time-data" data-link="class{merge:~isSelected() toggle='editing'}">
<span>{^{:daysLead}}</span>
</tr>
{{/for}}
And this JS:
function addNewLeadTimeClickHandler() {
var onNewLeadTimeClick = function () {
e.stopPropagation(); // this is what I was missing
var leadTime = {
daysLead: 1,
description: ''
};
$.observable(_model.activityMapping.leadTimes).insert(leadTime);
selectLeadtime(_model.activityMapping.leadTimes.length -1);
}
$leadTimes.on('click', '.add', onNewLeadTimeClick);
}
function selectLeadtime(index) {
var addStopEditingClickHandler = function () {
var onClickHandler = function (event) {
if ($(event.target).closest('tr').hasClass('editing')) {
setHandler();
return;
}
selectLeadtime(-1)
};
function setHandler() {
var clickEvent = 'click.ActivityChangeRequestDetailController-outside-edit-row';
$('html:not(.edit)').off(clickEvent).one(clickEvent, onClickHandler);
};
setHandler();
}
if (_model.selectedLeadtimeIndex !== index) {
$.observable(_model).setProperty('selectedLeadtimeIndex', index)
addStopEditingClickHandler();
}
}
function isSelected() {
var view = this;
return this.index === _model.selectedLeadtimeIndex;
}
// isSelected.depends = ["_model^selectedLeadtimeIndex"];
// for some reason I could not get the above .depends syntax to work
// ...or "_model.selectedLeadtimeIndex" or "_model.selectedLeadtimeIndex"
// but this worked ...
isSelected.depends = function() {return [_model, "selectedLeadtimeIndex"]};
The observable insert() method is synchronous. If your list items are rendered simply using {^{for}}, then that is also synchronous, so you should not need to use setTimeout, or a callback. (There are such callbacks available, but you should not need them for this scenario.)
See for example http://www.jsviews.com/#samples/editable/tags (code here):
$.observable(movies).insert({...});
// Set selection on the added item
app.select($.view(".movies tr:last").index);
The selection is getting added, synchronously, on the newly inserted item.
Do you have other asynchronous code somewhere in your rendering?
BTW generally you don't need to add new click handlers to added elements, if you use the delegate pattern. For example, in the same sample, a click handler to remove a movie is added initially to the container "#movieList" with a delegate selector ".removeMovie" (See code). That will work even for movies added later.
The same scenario works using {{on}} See http://www.jsviews.com/#link-events: "The selector argument can target elements that are added later"

how to pass parameter in jquery using .on?

Good Day, this maybe a silly question :) how can I pass a parameter to an external javascript function using .on ?
view:
<script>
var attachedPo = 0;
$this.ready(function(){
$('.chckboxPo').on('ifChecked', addPoToBill(attachedPo));
$('.chckboxPo').on('ifUnchecked', removePoToBill(attachedPo ));
});
</script>
external script:
function addPoToBill(attachedPo){
attachedPo++;
}
function removePoToBill(attachedPo){
attachedPo--;
}
but Im getting an error! thanks for guiding :)
You need to wrap your handlers in anonymous functions:
$('.chckboxPo')
.on('ifChecked', function() {
addPoToBill(attachedPo);
})
.on('ifUnchecked', function() {
removePoToBill(attachedPo);
});
You can also chain the calls to on as they are being attached to the same element.
If your intention is to count how many boxes are checked, via passing variable indirectly to functions try using an object instead like this:
JSFiddle: http://jsfiddle.net/TrueBlueAussie/pBkhX/
var attachedPo = {
count: 0
};
$(function () {
$('.chckboxPo')
.on('change', function () {
if ($(this).is(':checked')) {
addPoToBill(attachedPo);
} else {
removePoToBill(attachedPo);
}
$("#output").prepend("" + attachedPo.count + "<br/>");
});
});
function addPoToBill(attachedPo) {
attachedPo.count++;
}
function removePoToBill(attachedPo) {
attachedPo.count--;
}
If it is not doing anything else you can simplify the whole thing to count checked checkboxes:
$(function () {
var attachedPo = 0;
$('.chckboxPo')
.on('change', function () {
attachedPo = $(".chckboxPo:checked").length;
});
});
"DOM Ready" events:
you also needed to wrap it in a ready handler like this instead of what you have now:
$(function(){
...
});
*Note: $(function(){YOUR CODE HERE}); is just a shortcut for $(document).ready(function(){YOUR CODE HERE});
You can also do the "safer version" (that ensures a locally scoped $) like this:
jQuery(function($){
...
});
This works because jQuery passes a reference to itself through as the first parameter when your "on load" anonymous function is called.
There are other variations to avoid conflicts with other libraries (not very common as most modern libs know to leave $ to jQuery nowadays). Just look up jQuery.noConflict to find out more.

Defining generic function jquery

I have a simple function that shows a div when the user clicks on a given checkbox. I'd like to have the same behaviour on another checkbox, so that's why I'd like to generalize it as a function passing the element to be shown.
But I'm not aware of the syntax on Jquery to do so. And it's triggering automatically when the page loads. Does anybody has an idea?
Code:
$(document).ready(function() {
$("#transcricao").change(
function(){
if ($('.form_transcr').css('display') === 'none') {
$('.form_transcr').fadeIn();
} else {
$('.form_transcr').fadeOut();
}
}
); //This is working fine!
$("#traducao").change( show_hide($('.form_trad')) );
//This is auto-trigerring without user action...
});
Here's my function:
function show_hide($elm){
//This is the "generalized" function that I'd like to use on both
//checkboxes, just passing the element.
if ($($elm).css('display') === 'none') {
$($elm).fadeIn();
} else {
$($elm).fadeOut();
}
}
Its auto-triggering without user action because you are invoking it.
Use
$("#traducao").change(function () {
show_hide($('.form_trad'));
});
As you are passing jQuery object so use it directly
function show_hide($elm) {
//This is the "generalized" function that I'd like to use on both
//checkboxes, just passing the element.
if ($elm.css('display') === 'none') {
$elm.fadeIn();
} else {
$elm.fadeOut();
}
}
The argument to .change() should be a function. You're not passing a function, you're calling the function.
$("#traducao").change(function() {
show_hide($('.form_trad'));
} );
BTW, your show_hide function seems to be equivalent to jQuery's fadeToggle method, so it can be:
$("#traducao").change(function() {
$(".form_trad").fadeToggle();
});

How to check if a certain html fragment is already loaded?

Have the following code:
$("#blogs").mouseover(
function () {
$(this).addClass("hover");
$("#home").removeClass("hover");
$("#homepages").removeClass("hover");
$("#apps").removeClass("hover");
$("#facebook").removeClass("hover");
$("#kontakt").removeClass("hover");
$("#content").hide().load("blogs.html", function(){
$("#content").show("slide");
});
});
Works all fine, but now I would like the load() / show() function only be called if #content does not already contain blogs.html.
In other words: I would like to check if blogs.html is already loaded and if yes, simply do nothing and only if not there yet I would load and show it.
Have tried some things with hasClass() and some if-formulas but struggle to get this check.
Tried stuff like this:
$("#content section").hasClass("check_blog").hide().load("blogs.html", function(){
$("#content").show("slide");
Basically I just need to know how I can check if blogs.html is already the contents of #content.
Thanks a lot for any help. Regards, Andi
Add an ID to some element in blogs.html, say blogsloaded, then you can check for it with:
if (!$("#blogsloaded").length)
$("#content").hide().load("blogs.html" ...
Another method would be to store in a variable if you already loaded it:
if (!this.blogsloaded)
{
this.blogsloaded=true;
$("#content").hide().load("blogs.html" ...
}
I would split up your mouseover events into two namespaced events. One which will only run once.
// This event will only run once
$("#blogs").on("mouseover.runonce", function () {
$("#content").load("blogs.html");
});
// because this event will unbind the previous one
$("#blogs").on("mouseover.alwaysrun", function () {
$(this).off("mouseover.runonce");
$(this).addClass("hover");
$("#home").removeClass("hover");
$("#homepages").removeClass("hover");
$("#apps").removeClass("hover");
$("#facebook").removeClass("hover");
$("#kontakt").removeClass("hover");
$("#content").hide();
});​
Update a data attribute on #content that contains the url or id of the currently loaded content. Also, you should handle the case where the user hovers over a different section before the previous is done loading.
var request; // use this same var for all, don't re-declare it
$("#blogs").mouseover(function () {
// exit event if the blog is the current content in #content
if ( $("#content").data("current") == "blog") return;
$("#content").data("current","blog");
$(this).addClass("hover");
$("#home").removeClass("hover");
$("#homepages").removeClass("hover");
$("#apps").removeClass("hover");
$("#facebook").removeClass("hover");
$("#kontakt").removeClass("hover");
// if a previous request is still pending, abort it
if ($.isFunction(request.abort) && request.state() == "pending") request.abort();
// request content
request = $.get("blogs.html");
$("#content").hide();
// when content is done loading, update #content element
request.done(function(result){
$("#content").html(result);
});
});
I strongly suggest against using hover for loading content with ajax.
Also, in it's current form, this code is not very re-usable, you'll have to have one for each link. I suggest instead using classes and having only one event binding handling all of the links.
You can do it like this using .has() to detect descendants of content
$("#blogs").mouseover(
function () {
$(this).addClass("hover");
$("#home,#homepages,#apps,#facebook,#kontakt").removeClass("hover");
var $c = $("#content");
if($c.has('.check_blog')){ // if content contains an element with that class
$("#content").hide().load("blogs.html", function(){
$("#content").show("slide");
}
});
});
You could do something like this:
$("#blogs").mouseover(
function () {
$(this).addClass("hover");
$("#home").removeClass("hover");
$("#homepages").removeClass("hover");
$("#apps").removeClass("hover");
$("#facebook").removeClass("hover");
$("#kontakt").removeClass("hover");
if($('#content').html() == '') {
$("#content").hide().load("blogs.html", function(){
$("#content").show("slide");
});
}
});

Making my mouseevent coded in jquery a lot more elegant

I wrote this in order to fix the problem IE has with select drop down lists being truncated if their options were longer than the default value of the select. Now it works fine but I want to improve the code in order to learn how to write things in a much more useable fashion.
$(document).ready(function() {
if ($.browser.msie) {
$('select').focus(function() { $(this).addClass('expand').removeClass('clicked'); })
$('select').blur(function() { $(this).removeClass('expand clicked'); })
$('select').mousedown(function () { $(this).addClass('expand').removeClass('clicked'); } )
$('select').hover(function () { }, function () {if (!$(this).hasClass('clicked')) { $(this).removeClass('expand'); $(this.blur()) }})
$('select').click (function() { $(this).toggleClass('clicked'); })
$('select').change(function(){ $(this).removeClass('expand clicked'); $('select.widerIE').blur() })
}
});
I tried making functions which were called by each event but that seemed to fail eg:
$('select').click(test (a))
function test (a) {
$(a).addClass('expand').removeClass('clicked')
}
It's not clear to me what you're trying to achive. One thing is sure - you can't define a event handler like that (see note below):
$('select').click(test (a))
Note: Technically, you could define your event handler like in code above. For that to work, function test would have to return a function that would be actual handler for the event.

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