Develop Reference

Hide a div if an element has been clicked twice in a row, else Show

I have several items in my navigation bar, and a div next to it, ie:
<nav>
<a id="a"></a>
<a id="b"></a>
<a id="c"></a>
</nav>
<div id="menu-col"></div>
If the same link is clicked twice in a row, I want to hide #menu-col. If not, I want #menu-col to remain visible.
I'm not a javascript guy so I tried this:
var lastClicked;
$('nav a').on('click', function(e) {
alert(e.target.id + " - " + this.lastClicked);
if (e.target.id == this.lastClicked) {
$('#menu-col').hide();
this.lastClicked = '';
}
else {
$('#menu-col').show();
this.lastClicked = e.target.id;
}
});
Then I remembered that javascript assigns references, and not values. So when I did this.lastClicked = e.target.id; I'm assigning a reference to my element's id, then on the next click I make that e.target.id == ''.
In javascript, what would be the proper way of closing a box if the same link is clicked twice, and if not making sure the box is visible.

You can achieve this using toggleClass() to set a state class on the clicked a and also using toggle() on the .menu-col to show or hide it based on that state class. Try this:
$('nav a').click(function(e) {
e.preventDefault();
var $a = $(this);
$a.toggleClass('active').siblings().removeClass('active');
$('.menu-col').toggle($a.hasClass('active'));
});
.menu-col {
display: none;
}
.active {
color: #C00;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<nav>
<a id="a" href="#">a</a>
<a id="b" href="#">b</a>
<a id="c" href="#">c</a>
</nav>
<div class="menu-col">menu-col</div>

As long as you keep those ids unique across you app (which you should be doing anyway) the approach you've chosen isn't wrong. Any primitive in javascript is actually stored by value. Those primitives are string, number, boolean, and symbol. For more info see here https://developer.mozilla.org/en-US/docs/Glossary/Primitive

I would suggest something like this, you should have some kind of condition in which the div shows after it has been hidden.
$('nav a').dblclick(function(event) {
event.preventDefualt();
alert($(this).attr('id'));
$('#menu-col').toggle();
});
Something like that should be exactly what you are looking for, like I said though, there should be a condition in which it shows itself again, I made it a toggle so any double click on any 'nav a' element will cause it to show/hide the div.

Just for the sake of an option. Here is another way for double clicks(clicked twice in a row).
Using ondblclick event.
Double-click me.

Append element AFTER load

I've got this code
$(".test_init").click( function(){
var win = $(this).next(".test_wrap").find(".test_drop");
if ($(win).html().length)
$(win).empty().hide("fast");
else {
$(win).load("URL");
}
});
Which returns me some html form without close button
I wish to add close button using such method without adding it in every-single function
$('*[class*="_drop"]').change(function() {
$(this).append($('<a />', {
class: 'close-drop',
click: function(e) {
e.preventDefault();
alert("test");
}})
);
});
But nothing happens - i can't understand why close button doesn't appends
<div class="test_wrap relative">
<div class="test_drop absolute"></div>
</div>
Example: http://jsfiddle.net/fppfyey7/10/

Your problem is with your CSS, not with your JS. The button is appended but you are hidding it with your style.
For example in this fiddle I append a button with your JS code and your CSS:
Fiddle 1
Now, in this one, I just remove your absolute and relative classes:
Fiddle 2

My solution (isn't good enough, still works)
$('*[class*="_drop"]').ajaxStop(function() {
$(this).prepend('<a onclick="$(this).parent().empty().hide(\'fast\');" class="close-drop"></a>');
});
If here will be better solution, will mark it as answear!

How do I apply jQuery's slideToggle() to $(this) and do the opposite to all other elements?

What I'd like to do is have all elements of class collapsible_list not displayed by default (with one exception... see below*), and then toggle their display when their parent <div class="tab_box"> is clicked. During the same click, I'd also like for every other element of class collapsible_list to be hidden so that only one of them is expanded at any given time.
*Furthermore, when the page initially loads I'd also like to check to see if an element of collapsible_list has a child a element whose class is activelink, and if there is one then I'd like that link's parent collapsible_list element to be the one that's expanded by default.
Here's some sample html code:
<style>
.collapsible_list {
display: none;
}
.collapsible_list.active {
display: block;
}
</style>
<div id="sidebar">
<div class="tab_box">
<div class="collapsible_tab">2014</div>
<div class="collapsible_list panel-2014">
1
2
3
</div>
</div>
<div class="tab_box">
<div class="collapsible_tab">2013</div>
<div class="collapsible_list panel-2013">
<a class="activelink" href="/2013/1">1</a>
2
3
</div>
</div>
</div>
And here's where I'm currently at with the javascript (although I've tried a bunch of different ways and none have worked like I'd like them to):
$(document).ready(function() {
// This looks redundant to me but I'm not sure how else to go about it.
$(".collapsible_list").children("a.activelink").parent(".collapsible_list:not(.active)").addClass("active");
$(".tab_box").click(function() {
$(this).children(".collapsible_list").toggleClass("active").slideToggle("slow", function() {
$(".collapsible_list.active:not(this)").each(function() {
$(this).slideToggle("slow");
});
});
});
});
I hope that's not too confusing, but if it is then feel free to let me know. Any help is much appreciated.

Since you have a dom element reference that needs to be excluded use .not() instead of the :not() selector
jQuery(function ($) {
// This looks redundant to me but I'm not sure how else to go about it.
$(".collapsible_list").children("a.activelink").parent(".collapsible_list:not(.active)").addClass("active").show();
$(".tab_box").click(function () {
var $target = $(this).children(".collapsible_list").toggleClass("active").stop(true).slideToggle("slow");
//slidup others
$(".collapsible_list.active").not($target).stop(true).slideUp("slow").removeClass('active');
});
});
Also, instead of using the slide callback do it directly in the callback so that both the animations can run simultaniously
Also remove the css rule .collapsible_list.active as the display is controlled by animations(slide)

Try This.
$('.collapsible_tab a').on('click', function(e){
e.preventDefault();
$('.collapsible_list').removeClass('active')
$(this).parent().next('.collapsible_list').toggleClass('active');
});
Fiddle Demo

I think your code would be less complicated if you simply remembered the previously opened list:
jQuery(function($) {
// remember current list and make it visible
var $current = $('.collapsible_list:has(.activelink)').show();
$(".tab_box").on('click', function() {
var $previous = $current;
// open new list
$current = $('.collapsible_list', this)
.slideToggle("slow", function() {
// and slide out the previous
$previous.slideToggle('slow');
});
});
});
Demo

how to repeat same Javascript code over multiple html elements

Note: Changed code so that images and texts are links.
Basically, I have 3 pictures all with the same class, different ID. I have a javascript code which I want to apply to all three pictures, except, the code needs to be SLIGHTLY different depending on the picture. Here is the html:
<div class=column1of4>
<img src="images/actual.jpg" id="first">
<div id="firsttext" class="spanlink"><p>lots of text</p></div>
</div>
<div class=column1of4>
<img src="images/fake.jpg" id="second">
<div id="moretext" class="spanlink"><p>more text</p></div>
</div>
<div class=column1of4>
<img src="images/real.jpg" id="eighth">
<div id="evenmoretext" class="spanlink"><p>even more text</p></div>
</div>
Here is the Javascript for the id="firsttext":
$('#firstextt').hide();
$('#first, #firsttext').hover(function(){
//in
$('#firsttext').show();
},function(){
//out
$('#firsttext').hide();
});
So when a user hovers over #first, #firsttext will appear. Then, I want it so that when a user hovers over #second, #moretext should appear, etc.
I've done programming in Python, I created a sudo code and basically it is this.
text = [#firsttext, #moretext, #evenmoretext]
picture = [#first, #second, #eighth]
for number in range.len(text) //over here, basically find out how many elements are in text
$('text[number]').hide();
$('text[number], picture[number]').hover(function(){
//in
$('text[number]').show();
},function(){
//out
$('text[number]').hide();
});
The syntax is probably way off, but that's just the sudo code. Can anyone help me make the actual Javascript code for it?

try this
$(".column1of4").hover(function(){
$(".spanlink").hide();
$(this).find(".spanlink").show();
});

Why not
$('.spanlink').hide();
$('.column1of4').hover(
function() {
// in
$(this).children('.spanlink').show();
},
function() {
// out
$(this).children('.spanlink').hide();
}
);
It doesn't even need the ids.

You can do it :
$('.column1of4').click(function(){
$(this); // the current object
$(this).children('img'); // img in the current object
});
or a loop :
$('.column1of4').each(function(){
...
});
Dont use Id as $('#id') for multiple events, use a .class or an [attribute] do this.

If you're using jQuery, this is quite easy to accomplish:
$('.column1of4 .spanlink').hide();
$('.column1of4 img').mouseenter(function(e){
e.stopPropagation();
$(this).parent().find('.spanlink').show();
});
$('.column1of4 img').mouseleave(function(e){
e.stopPropagation();
$(this).parent().find('.spanlink').hide();
});

Depending on your markup structure, you could use DOM traversing functions like .filter(), .find(), .next() to get to your selected node.
$(".column1of4").hover(function(){
$(".spanlink").hide();
$(this).find(".spanlink, img").show();
});

So, the way you would do this, given your html would look like:
$('.column1of4').on('mouseenter mouseleave', 'img, .spanlink', function(ev) {
$(ev.delegateTarget).find('.spanlink').toggle(ev.type === 'mouseenter');
}).find('.spanlink').hide();
But building on what you have:
var text = ['#firsttext', '#moretext', '#evenmoretext'];
var picture = ['#first', '#second', '#third'];
This is a traditional loop using a closure (it's better to define the function outside of the loop, but I'm going to leave it there for this):
// You could also do var length = text.length and replace the "3"
for ( var i = 0; i < 3; ++i ) {
// create a closure so that i isn't incremented when the event happens.
(function(i) {
$(text[i]).hide();
$([text[i], picture[i]].join(',')).hover(function() {
$(text[i]).show();
}, function() {
$(text[i]).hide();
});
})(i);
}
And the following is using $.each to iterate over the group.
$.each(text, function(i) {
$(text[i]).hide();
$([text[i], picture[i]].join(', ')).hover(function() {
$(text[i]).show();
}, function() {
$(text[i]).hide();
});
});
Here's a fiddle with all three versions. Just uncomment the one you want to test and give it a go.

I moved the image inside the div and used this code, a working example:
$('.column1of4').each(function(){
$('div', $(this)).each(function(){
$(this).hover(
function(){
//in
$('img', $(this)).show();
},
function(){
//out
$('img', $(this)).hide();
});
});
});
The general idea is 1) use a selector that isn't an ID so I can iterate over several elements without worrying if future elements will be added later 2) locate the div to hide/show based on location relational to $(this) (will only work if you repeat this structure in your markup) 3) move the image tag inside the div (if you don't, then the hover gets a little spazzy because the positioned is changed when the image is shown, therefore affecting whether the cursor is inside the div or not.
EDIT
Updated fiddle for additional requirements (see comments).

How to detect mouseleave() on two elements at once?

Answer can be in vanilla js or jQuery. I want to hide a div with the id "myDiv" if the user is no longer hovering over a link with the id "myLink" or a span with the id "mySpan". If the user has his mouse over either element "myDiv" will still show, but the second the user is not hover over either of the two (doesn't matter which element the user's mouse leaves first) "myDiv" will disappear from the face of existence.
In other words this is how I detect mouse leave on one element:
$('#someElement').mouseleave(function() {
// do something
});
but how to say (in a way that will actually work):
$('#someElement').mouseleave() || $('#someOtherElement').mouseleave()) {
// do something
});
How to detect this?

Something like this should work:
var count = 0;
$('#myLink, #mySpan').mouseenter(function(){
count++;
$('#myDiv').show();
}).mouseleave(function(){
count--;
if (!count) {
$('#myDiv').hide();
}
});
jsfiddle

You could use a multiple selector:
$("#someElement, #someOtherElement").mouseleave(function() {
// Do something.
});

You can beautifully use setTimeout() to give the mouseleave() function some "tolerance", that means if you leave the divs but re-enter one of them within a given period of time, it does not trigger the hide() function.
Here is the code (added to lonesomeday's answer):
var count = 0;
var tolerance = 500;
$('#d1, #d2').mouseenter(function(){
count++;
$('#d3').show();
}).mouseleave(function(){
count--;
setTimeout(function () {
if (!count) {
$('#d3').hide();
}
}, tolerance);
});
http://jsfiddle.net/pFTfm/195/

I think, it's your solution!!!
$(document).ready(function() {
var someOtherElement = "";
$("#someElement").hover(function(){
var someOtherElement = $(this).attr("href");
$(someOtherElement).show();
});
$("#someElement").mouseleave(function(){
var someOtherElement= $(this).attr("href");
$(someOtherElement).mouseenter(function(){
$(someOtherElement).show();
});
$(someOtherElement).mouseleave(function(){
$(someOtherElement).hide();
});
});
});
----
html
----
<div id="someElement">
<ul>
<li>element1</li>
<li>element2</li>
</ul>
</div>
<div id="tab1" style="display: none"> TAB1 </div>
<div id="tab2" style="display: none"> TAB1 </div>

While the answer from lonesomeday is perfectly valid I changed my html to have both elements in one container. I originally wanted to avoid this hence I had to do more refactoring for my clients in other html templates, but I think it will pay out on the long term.
<div id="my-container">
<div class="elem1">Foo</div>
<div class="elem2">Bar</div>
</div>
$('#my-container').mouseleave(function() { console.log("left"); });