Develop Reference

Photoswipe 4.0: Initiate 'swipe to next' programatically

SITUATION
I have been trying to trigger the 'slide to next picture' animation when the NEXT button is clicked, but i have not found a solution for this.
There is an ongoing discussion about this on GitHub, but it is only about adding the option for a slide animation, not about how to actually do it with PS as it is right now.
There was an option for it in 3.0 but as 4.0 is a complete rewrite it does not work anymore.
QUESTION
Instead of just 'jumping' to the next/prev picture when an arrow is clicked, i need the 'slide transition' that is also used when swiping/dragging the image.
There is no option to trigger that, so how can i manually trigger this effect with JS?

PhotoSwipe Slide Transitions
So, I added slide transitions to Photoswipe, and it's working nicely without disturbing native behavior.
http://codepen.io/mjau-mjau/full/XbqBbp/
http://codepen.io/mjau-mjau/pen/XbqBbp
The only limitation is that transition will not be applied between seams in loop mode (for example when looping from last slide to slide 1). In examples I have used jQuery.
Essentially, it works by simply adding a CSS transition class to the .pswp__container on demand, but we need to add some javascript events to prevent the transition from interfering with Swipe, and only if mouseUsed. We also add a patch so the transition does not get added between loop seams.
1. Add the below to your CSS
It will be applied on-demand from javascript when required.
.pswp__container_transition {
-webkit-transition: -webkit-transform 333ms cubic-bezier(0.4, 0, 0.22, 1);
transition: transform 333ms cubic-bezier(0.4, 0, 0.22, 1);
}
2. Add javascript events to assist in assigning the transition class
This can go anywhere, but must be triggered after jQuery is loaded.
var mouseUsed = false;
$('body').on('mousedown', '.pswp__scroll-wrap', function(event) {
// On mousedown, temporarily remove the transition class in preparation for swipe. $(this).children('.pswp__container_transition').removeClass('pswp__container_transition');
}).on('mousedown', '.pswp__button--arrow--left, .pswp__button--arrow--right', function(event) {
// Exlude navigation arrows from the above event.
event.stopPropagation();
}).on('mousemove.detect', function(event) {
// Detect mouseUsed before as early as possible to feed PhotoSwipe
mouseUsed = true;
$('body').off('mousemove.detect');
});
3. Add beforeChange listener to re-assign transition class on photoswipe init
The below needs to be added in your PhotoSwipe init logic.
// Create your photoswipe gallery element as usual
gallery = new PhotoSwipe(pswpElement, PhotoSwipeUI_Default, items, options);
// Transition Manager function (triggers only on mouseUsed)
function transitionManager() {
// Create var to store slide index
var currentSlide = options.index;
// Listen for photoswipe change event to re-apply transition class
gallery.listen('beforeChange', function() {
// Only apply transition class if difference between last and next slide is < 2
// If difference > 1, it means we are at the loop seam.
var transition = Math.abs(gallery.getCurrentIndex()-currentSlide) < 2;
// Apply transition class depending on above
$('.pswp__container').toggleClass('pswp__container_transition', transition);
// Update currentSlide
currentSlide = gallery.getCurrentIndex();
});
}
// Only apply transition manager functionality if mouse
if(mouseUsed) {
transitionManager();
} else {
gallery.listen('mouseUsed', function(){
mouseUsed = true;
transitionManager();
});
}
// init your gallery per usual
gallery.init();

You can just use a css transition:
.pswp__container{
transition:.3s ease-in-out all;
}
This might not be ideal for performance on mobile, but I just add this transition in a media query and allow users to use the swipe functionality on smaller screens.

I finally bit the bullet and spent some time making this work as nobody seemed to have a solution for that, not here neither on GitHub or anywhere else.
SOLUTION
I used the fact that a click on the arrow jumps to the next item and triggers the loading of the next image and sets the whole slide state to represent the correct situation in an instant.
So i just added custom buttons which would initiate a slide transition and then triggered a click on the original buttons (which i hid via CSS) which would update the slide state to represent the situation i created visually.
Added NEW next and prev arrows
Hid the ORIGINAL next and prev arrows via css
Animated the slide myself when the NEW next or prev arrows were clicked
Then triggered the click on the ORIGINAL next or prev arrows programmatically
So here is the code:
HTML
// THE NEW BUTTONS
<button class="NEW-button-left" title="Previous (arrow left)">PREV</button>
<button class="NEW-button-right" title="Next (arrow right)">NEXT</button>
// added right before this original lines of the example code
<button class="pswp__button pswp__button--arrow--left ...
CSS
pswp__button--arrow--left,
pswp__button--arrow--right {
display: none;
}
NEW-button-left,
NEW-button-right {
/* whatever you fancy */
}
JAVASCRIPT (helper functions)
var tx = 0; // current translation
var tdir = 0;
var slidepseactive = false;
// helper function to get current translate3d positions
// as per https://stackoverflow.com/a/7982594/826194
function getTransform(el) {
var results = $(el).css('-webkit-transform').match(/matrix(?:(3d)\(-{0,1}\d+(?:, -{0,1}\d+)*(?:, (-{0,1}\d+))(?:, (-{0,1}\d+))(?:, (-{0,1}\d+)), -{0,1}\d+\)|\(-{0,1}\d+(?:, -{0,1}\d+)*(?:, (-{0,1}\d+))(?:, (-{0,1}\d+))\))/)
if(!results) return [0, 0, 0];
if(results[1] == '3d') return results.slice(2,5);
results.push(0);
return results.slice(5, 8);
}
// set the translate x position of an element
function translate3dX($e, x) {
$e.css({
// TODO: depending on the browser we need one of those, for now just chrome
//'-webkit-transform': 'translate3d(' +String(x) + 'px, 0px, 0px)'
//, '-moz-transform': 'translate3d(' +String(x) + 'px, 0px, 0px)'
'transform': 'translate3d(' +String(x) + 'px, 0px, 0px)'
});
};
JAVASCRIPT (main)
// will slide to the left or to the right
function slidePS(direction) {
if (slidepseactive) // prevent interruptions
return;
tdir = -1;
if (direction == "left") {
tdir = 1;
}
// get the current slides transition position
var t = getTransform(".pswp__container");
tx = parseInt(t[0]);
// reset anim counter (you can use any property as anim counter)
$(".pswp__container").css("text-indent", "0px");
slidepseactive = true;
$(".pswp__container").animate(
{textIndent: 100},{
step: function (now, fx) {
// here 8.7 is the no. of pixels we move per animation step %
// so in this case we slide a total of 870px, depends on your setup
// you might want to use a percentage value, in this case it was
// a popup thats why it is a a fixed value per step
translate3dX($(this), tx + Math.round(8.7 * now * tdir));
},
duration: '300ms',
done: function () {
// now that we finished sliding trigger the original buttons so
// that the photoswipe state reflects the new situation
slidepseactive = false;
if (tdir == -1)
$(".pswp__button--arrow--right").trigger("click");
else
$(".pswp__button--arrow--left").trigger("click");
}
},
'linear');
}
// now activate our buttons
$(function(){
$(".NEW-button-left").click(function(){
slidePS("left");
});
$(".NEW-button-right").click(function(){
slidePS("right");
});
});
I used info from those SE answers:
jQuery animate a -webkit-transform
Get translate3d values of a div?

The PhotoSwipe can do this by itself when you use swipe gesture. So why not to use the internal code instead of something that doesn't work well?
With my solution everything works well, the arrow clicks, the cursor keys and even the loop back at the end and it doesn't break anything.
Simply edit the photoswipe.js file and replace the goTo function with this code:
goTo: function(index) {
var itemsDiff;
if (index == _currentItemIndex + 1) { //Next
itemsDiff = 1;
}
else { //Prev
itemsDiff = -1;
}
var itemChanged;
if(!_mainScrollAnimating) {
_currZoomedItemIndex = _currentItemIndex;
}
var nextCircle;
_currentItemIndex += itemsDiff;
if(_currentItemIndex < 0) {
_currentItemIndex = _options.loop ? _getNumItems()-1 : 0;
nextCircle = true;
} else if(_currentItemIndex >= _getNumItems()) {
_currentItemIndex = _options.loop ? 0 : _getNumItems()-1;
nextCircle = true;
}
if(!nextCircle || _options.loop) {
_indexDiff += itemsDiff;
_currPositionIndex -= itemsDiff;
itemChanged = true;
}
var animateToX = _slideSize.x * _currPositionIndex;
var animateToDist = Math.abs( animateToX - _mainScrollPos.x );
var finishAnimDuration = 333;
if(_currZoomedItemIndex === _currentItemIndex) {
itemChanged = false;
}
_mainScrollAnimating = true;
_shout('mainScrollAnimStart');
_animateProp('mainScroll', _mainScrollPos.x, animateToX, finishAnimDuration, framework.easing.cubic.out,
_moveMainScroll,
function() {
_stopAllAnimations();
_mainScrollAnimating = false;
_currZoomedItemIndex = -1;
if(itemChanged || _currZoomedItemIndex !== _currentItemIndex) {
self.updateCurrItem();
}
_shout('mainScrollAnimComplete');
}
);
if(itemChanged) {
self.updateCurrItem(true);
}
return itemChanged;
},

Using a jquery slider for text instead of images?

This may be a little too specific, but I have a jquery slider that I am using <p> classes instead of images to cycle through customer quotes. Basically the problem I am running into right now is when it is static and non moving (JS code is commeneted out) they are aligned how I want them to be. As soon as the JS is un commented, they stretch out of view and you just see a white box?
Any ideas?
How I want each panel to look like:
jsfiddle

So I sort of made this my Friday project. I've changed a whole lot of your code, and added a vertical-align to the quotes and authors.
Here's the fiddle http://jsfiddle.net/qLca2fz4/49/
I added a whole lot of variables to the top of the script so you could less typing throughout.
$(document).ready(function () {
//rotation speed and timer
var speed = 5000;
var run = setInterval(rotate, speed);
var slides = $('.slide');
var container = $('#slides ul');
var elm = container.find(':first-child').prop("tagName");
var item_width = container.width();
var previous = 'prev'; //id of previous button
var next = 'next'; //id of next button
Since you used a % based width I'm setting the pixel widths of the elements in case the screen is reszed
slides.width(item_width); //set the slides to the correct pixel width
container.parent().width(item_width);
container.width(slides.length * item_width); //set the slides container to the correct total width
As you had, I'm rearranging the slides in the event the back button is pressed
container.find(elm + ':first').before(container.find(elm + ':last'));
resetSlides();
I combined the prev and next click events into a single function. It checks for the ID of the element targeted in the click event, then runs the proper previous or next functions. If you reset the setInterval after the click event your browser has trouble stopping it on hover.
//if user clicked on prev button
$('#buttons a').click(function (e) {
//slide the item
if (container.is(':animated')) {
return false;
}
if (e.target.id == previous) {
container.stop().animate({
'left': 0
}, 1500, function () {
container.find(elm + ':first').before(container.find(elm + ':last'));
resetSlides();
});
}
if (e.target.id == next) {
container.stop().animate({
'left': item_width * -2
}, 1500, function () {
container.find(elm + ':last').after(container.find(elm + ':first'));
resetSlides();
});
}
//cancel the link behavior
return false;
});
I've found mouseenter and mouseleave to be a little more reliable than hover.
//if mouse hover, pause the auto rotation, otherwise rotate it
container.parent().mouseenter(function () {
clearInterval(run);
}).mouseleave(function () {
run = setInterval(rotate, speed);
});
I broke this in to its own function because it gets called in a number of different places.
function resetSlides() {
//and adjust the container so current is in the frame
container.css({
'left': -1 * item_width
});
}
});
//a simple function to click next link
//a timer will call this function, and the rotation will begin :)
And here's your rotation timer.
function rotate() {
$('#next').click();
}

It took me a little bit, but I think I figured out a few things.
http://jsfiddle.net/qLca2fz4/28/
First off, your console was throwing a few errors: first, that rotate wasn't defined and that an arrow gif didn't exist. Arrow gif was probably something you have stored locally, but I changed the 'rotate' error by changing the strings in the code here to your actual variables.
So, from:
run = setInterval('rotate()', speed);
We get:
run = setInterval(rotate, speed);
(No () based on the examples here: http://www.w3schools.com/jsref/met_win_setinterval.asp)
But I think a more important question is why your text wasn't showing up at all. It's because of the logic found here:
$('#slides ul').css({'left' : left_value});
You even say that this is setting the default placement for the code. But it isn't..."left_vaule" is the amount that you've calculated to push left during a slide. So if you inspect the element, you can see how the whole UL is basically shifted one slide's worth too far left, unable to be seen. So we get rid of 'left_value', and replace it with 0.
$('#slides ul').css({'left' : 0});
Now, there's nothing really handling how the pictures slide in, so that part's still rough, but this should be enough to start on.
Let me know if I misunderstood anything, or if you have any questions.

So, a few things:
1) I believe you are trying to get all of the lis to be side-by-side, not arranged up and down. There are a few ways to do this. I'd just make the ul have a width of 300%, and then make the lis each take up a third of that:
#slides ul {
....
width: 300%;
}
#slides li {
width: calc(100% / 3);
height:250px;
float:left;
}
2) You got this right, but JSFiddle automatically wraps all your JS inside a $(document).ready() handler, and your function, rotate needs to be outside, in the normal DOM. Just change that JSFiddle setting from 'onload' to 'no wrap - in head'
3) Grabbing the CSS value of an element doesn't always work, especially when you're dealing with animating elements. You already know the width of the li elements with your item_width variable. I'd just use that and change your code:
var left_indent = parseInt($('#slides ul').css('left')) - item_width;
$('#slides ul').animate({'left' : left_indent}, 1500, function () {
to:
$('#slides ul').stop().animate({'left' : -item_width * 2}, 1500, function () {
4) Throw in the .stop() as seen in the above line. This prevents your animations from overlapping. An alternative, and perhaps cleaner way to do this, would be to simply return false at the beginning of your 'next' and 'prev' functions if #slides ul is being animated, like so:
if ($('#slides ul').is(':animated')) return false;
And I think that's everything. Here's the JSFiddle. Cheers!
EDIT:
Oh, and you may also want to clearInterval at the beginning of the next and prev functions and then reset it in the animation callback functions:
$('#prev').click(function() {
if ($('#slides ul').is(':animated')) return false;
clearInterval(run);
$('#slides ul').stop().animate({'left' : 0}, 1500,function(){
....
run = setInterval('rotate()', speed);
});
});

Javascript fade in doesn't visibly animate

So I've created the following function to fade elements in and passed in a div that I want to fade in which in this case is an image gallery popup that I want to show when a user clicks an image thumbnail on my site. I'm also passing in a speed value (iSpeed) which the timeout uses for it's time value. In this case I'm using 25 (25ms).
I've stepped through this function whilst doing so it appears to be functioning as expected. If the current opacity is less than 1, then it is incremented and it will recall itself after the timeout until the opacity reaches 1. When it reaches one it stops fading and returns.
So after stepping through it, I take off my breakpoints and try to see it in action but for some reason my gallery instantly appears without any sense of fading.
var Effects = new function () {
this.Fading = false;
this.FadeIn = function (oElement, iSpeed) {
//set opacity to zero if we haven't started fading yet.
if (this.Fading == false) {
oElement.style.opacity = 0;
}
//if we've reached or passed max opacity, stop fading
if (oElement.style.opacity >= 1) {
oElement.style.opacity = 1;
this.Fading = false;
return;
}
//otherwise, fade
else {
this.Fading = true;
var iCurrentOpacity = parseFloat(oElement.style.opacity);
oElement.style.opacity = iCurrentOpacity + 0.1;
setTimeout(Effects.FadeIn(oElement, iSpeed), iSpeed);
}
}
}
Here's where I'm setting up the gallery.
this.Show = function (sPage, iImagesToDisplay, oSelectedImage) {
//create and show overlay
var oOverlay = document.createElement('div');
oOverlay.id = 'divOverlay';
document.body.appendChild(oOverlay);
//create and show gallery box
var oGallery = document.createElement('div');
oGallery.id = 'divGallery';
oGallery.style.opacity = 0;
document.body.appendChild(oGallery);
//set position of gallery box
oGallery.style.top = (window.innerHeight / 2) - (oGallery.clientHeight / 2) + 'px';
oGallery.style.left = (window.innerWidth / 2) - (oGallery.clientWidth / 2) + 'px';
//call content function
ImageGallery.CreateContent(oGallery, sPage, iImagesToDisplay, oSelectedImage);
//fade in gallery
Effects.FadeIn(oGallery, 25);
}
Could anyone help me out?
Also, I'm using IE10 and I've also tried Chrome, same result.
Thanks,
Andy

This line:
setTimeout(Effects.FadeIn(oElement, iSpeed), iSpeed);
calls Effects.FadeIn with the given arguments, and feeds its return value into setTimeout. This is exactly like foo(bar()), which calls bar immediately, and then feeds its return value into foo.
Since your FadeIn function doesn't return a function, that would be the problem.
Perhaps you meant:
setTimeout(function() {
Effects.FadeIn(oElement, iSpeed);
}, iSpeed);
...although you'd be better off creating that function once and reusing it.
For instance, I think this does what you're looking for, but without recreating functions on each loop:
var Effects = new function () {
this.FadeIn = function (oElement, iSpeed) {
var fading = false;
var timer = setInterval(function() {
//set opacity to zero if we haven't started fading yet.
if (fading == false) { // Consider `if (!this.Fading)`
oElement.style.opacity = 0;
}
//if we've reached or passed max opacity, stop fading
if (oElement.style.opacity >= 1) {
oElement.style.opacity = 1;
clearInterval(timer);
}
//otherwise, fade
else {
fading = true;
var iCurrentOpacity = parseFloat(oElement.style.opacity);
oElement.style.opacity = iCurrentOpacity + 0.1;
}
}, iSpeed);
};
};

Your code has a lot of problems. The one culpable for the element appearing immediately is that you call setTimeout not with a function but with the result of a function, because Effects.FadeIn will be executed immediately.
setTimeout(function(){Effects.FadeIn(oElement, iSpeed)}, iSpeed);
will probably act as you intend.
But seriously, you probably should not re-invent this wheel. jQuery will allow you to fade elements in and out easily and CSS transitions allow you to achieve element fading with as much as adding or removing a CSS class.

T.J. and MoMolog are both right about the bug: you're invoking the Effects.FadeIn function immediately before passing the result to setTimeout—which means that Effects.FadeIn calls itself synchronously again and again until the condition oElement.style.opacity >= 1 is reached.
As you may or may not know, many UI updates that all take place within one turn of the event loop will be batched together on the next repaint (or something like that) so you won't see any sort of transition.
This jsFiddle includes the suggested JS solution, as well as an alternate approach that I think you may find to be better: simply adding a CSS class with the transition property. This will result in a smoother animation. Note that if you go this route, though, you may need to also include some vendor prefixes.

Image Rotation using pure Javascript

PLEASE DO NOT RECOMMEND JQUERY - I AM DOING THIS EXERCISE FOR LEARNING PURPOSES.
I have implemented a JavaScript, which rotates images (_elementSlideChange) on a timer, using a set interval of 10 seconds. Also I have added a slide functionality to this, which is 7 milliseconds (_slideImage).
The image rotates automatically every 10 seconds on page load, and I have also provided next and previous buttons, which allow the user to change the images manually.
_elementSlideChange: function () {
var myString;
var myText;
for (var i = 0; i < this._imgArray.length; i++) {
var imageArr = "url(" + this._imgArray[i].src + ")";
var imageBg = this._imageHolder.style.background + "";
if (imageArr == imageBg) {
if (i == (this._imgArray.length - 1)) {
myString = "url(" + this._imgArray[0].src + ")";
myText = this._infoArray[0];
} else {
myString = "url(" + this._imgArray[(i + 1)].src + ")";
myText = this._infoArray[i + 1];
}
}
}
this._imageNextSlide.style.background = myString;
this._imageNextSlide.style.background);
this._infoElement.innerHTML = myText;
this._myTimer = setInterval(MyProject.Utils.createDelegate(this._slideImage, this), 7);
},
_slideImage: function () {
if (parseInt(this._imageHolder.style.width) >= 0 && parseInt(this._imageNextSlide.style.width) <= 450) {
this._imageHolder.style.backgroundPosition = "right";
this._imageHolder.style.width = (parseInt(this._imageHolder.style.width) - 1) + 'px';
console.log(this._imageNextSlide.style.background);
this._imageNextSlide.style.width = (parseInt(this._imageNextSlide.style.width) + 1) + 'px';
} else {
console.log("reached 0px");
if (parseInt(this._imageHolder.style.width) == 0) {
this._imageHolder.style.background = this._imageNextSlide.style.background;
this._imageHolder.style.width = 450 + 'px';
this._imageHolder === this._imageNextSlide;
this._imageHolder.className = "orginalImage";
this._imageNextSlide.style.width = 0 + "px";
this._imageNextSlide = this._dummyImageNextSlide;
this._imagesElement.appendChild(this._imageHolder);
this._imagesElement.appendChild(this._imageNextSlide);
clearInterval(this._myTimer);
}
clearInterval(this._myTimer);
clearInterval(this._elementSlideChange);
}
}
So when the user clicks on the Next arrow button, the event listener for "click" is triggered. This creates a div for the current image on display, and creates a new div, which will contain the next image. The image slide and rotation works correctly (whether it's onLoad or onClick). The issue I have is if I click the Next button, while the new div image is sliding into position, it causes it to run into an infinite loop, so the same div with the image to be displayed keeps sliding in, and the more you click the Next button, the faster the image starts to rotate.
I have tried putting a clear interval for the image rotation and slider, but I do understand my code is wrong, which causes the infinite loop of the sliding image. And I know I am close to finishing the functionality.
Can anyone please advise where I could be going wrong? Or should I try to implement the sliding DIV in another way?
Once again please don't recommend jQuery.
And thank you for your help in advance.
Kush

To solve the issue, I did re-write the entire code, where I had a next and previous button event listener.
myProject.Utils.addHandler(this._nextImageElement, "click", myProject.Utils.createDelegate(this._changeImage, this));
Both the buttons will call the same function :
_changeImage: function (e)
In this function I check to see if the function is Transition (changing images),
I declare a boolean var forward = e.target == this._nextImageElement;
Then check to see the current index if forward ? Add 1 else minus 1
this._currentImageIndex += forward ? 1 : -1;
If its at the end of the Array and forward is true, assign the this._currentImageIndex to reset to 0 or Array.length – 1 if it’s in reverse
Then call another function which gives the ‘div’ a sliding effect. In this case call it this._transitionImage(forward);
In this function, set the this._inTranstion to true. (Because the div’s are sliding in this case).
The following code solved the issue i was having.
this._slideImageElement.style.backgroundImage = "url(\"" + this._imgArray[this._currentImageIndex].src + "\")";
this._slideImageElement.style.backgroundPosition = forward ? "left" : "right";
this._slideImageElement.style.left = forward ? "auto" : "0px";
this._slideImageElement.style.right = forward ? "0px" : "auto";
The above code is very important as the object is to place the “sliding in div” Left or Right of the current Visible “div” to the user, and this is mainly dependent on if the forward variable is true or false.
var i = 0;
Then start the transition by
setInterval( function() {
this._currentImageElement.style.backgroundPosition = (forward ? -1 : 1) * (i + 1) + "px";
this._slideImageElement.style.width = (i + 1) + "px";
Notice the forward will determine if the bgPosition will go to the left if its forward as we multiple by -1 or +1,
So for example
If the user clicks NEXT BUTTON,
Forward = true
So the first thing we do is set the
this._slideImageElement.style.backgroundPosition = "left"
Then
this._slideImageElement.style.left = "auto"
this._slideImageElement.style.right = "0px"
This means when the sliding image moves in its background position is LEFT but the div is placed on the RIGHT to 0px;
then this._currentImageElement.style.backgroundPosition = -1 * (i + 1)
Which moves the position of the currentImageElement to the left by 1px,
Increase the width of the slideImage which in this case is right of the current div,
and as the current div moves to the left the sliding image starts to appear from the right. (By default set the width of slideImageElement to 0px so the div exists but isn’t visible to the user). This gives it the slide effect of moving forward new image coming from the right.
this._slideImageElement.style.width = (i + 1) + "px";
then declare it to stop when it it’s the image width. In this case it will be 500px.
if ((i = i + 2) == 500) {
In this if statement reset the currentImageElement background and the background position “right” or “left” don’t really matter as long it has been reset.
Clear the interval
Set the transition to false again
Then call a setTimeout for the function changeImage, which will continue until the slide is completed.
The following shows the reset code as this is very important to prevent repeating the same image (This solved my entire issue)
// set the current image to the "new" current image and reset it's background position
this._currentImageElement.style.backgroundImage = "url(\"" + this._imgArray[this._currentImageIndex].src + "\")";
this._currentImageElement.style.backgroundPosition = "right";
// reset the slide image width
this._slideImageElement.style.width = "0px";
// clear the transition interval and mark as not in transition
clearInterval(this._transitionInterval);
this._inTransition = false;
// setup the next image timer
this._nextImageTimeout = setTimeout(myProject.Utils.createDelegate(this._changeImage, this), 2500);
}
I have provided a thorough detail because then it easier to understand the logic of the problem, and even if your not having the same issue, this may help you fingure out any problem.
I couldn't provide a JSfiddle, as i have created my CSS using Javascript, there are different ways of doing this, but i wanted to understand the logic behind the forward and reverse, and having a timer which continuously goes forward.

It seems like you want to cancel the animation on the slide (perhaps have it fade out while the next slide animates in, cancel its animation abruptly or let it finish and ignore the button click)
What I usually do, personally, is check for the animated state (yes, I use jquery, but you should be able to test the CSS or positioning values you are using to animate in the same way) you could even add an "active" class or data type during animation to make testing easier. Global flags work, too. If there is animation, ignore the button. (For my work... Depends on your intention)
Like I said, the problem may be with button behaviour not with the animation routine. It would be useful to see how you are calling this from the button click, and what your intended results are going to be.

How about CSS3 transitions?
transition: all 1s ease 0.5s;
Simple example on JS Fiddle.
This takes care of the animation, so you just need to set the intended destination using JavaScript, i.e.
this.style.left = '100px';
Or
this.style.top = '30px';
And CSS3 transitions will smoothly slide the element.
Cross Browser Note!
The transition property may need a vendor prefix for some browsers, I am using the latest production Firefox and you don't need -moz for that. Same goes for Opera, no '-o' required. Internet Exporer 10 needs no prefix. You may need to use -webkit for Safari / Chrome, but test without first.

Fixing the animation properties

I am doing some research at the moment into creating a new maths game for primary school children where divs from 0-9 appear at random inside a container.
A question is given at the beginning. Something like, multiples of 20. The user will then have to click on the correct ones, and they will then be counted at the end and a score will be given.
I have just changed the speed in which the divs appear so that they appear for longer and more than one at a time to make the game easier for younger children.
I used "fadeIn" like so..
$('#' + id).animate({
top: newY,
left: newX
}, 'slow', function() {}).fadeIn(2000);
}
My problem is that now when I shoot the correct or incorrect number the animation is very glitchy and I cannot figure out why.
Fiddle: http://jsfiddle.net/cFKHq/6/ (See version 5 to see what it was like before)

Inside startplay(), control the concurrency when calling scramble() , I do it with a global var named window.cont, so I replaced your following call:
play = setInterval(scramble, 1800);
for this one:
play = setInterval(function() {
if (window.cont){
window.cont = false;
scramble();
}
}, 1000);
The var window.cont needs to be set globally at the start of your code, like so:
var miss = 0;
var hit = 0;
var target = $("#target");
window.cont = true;
So with window.cont you now can control that animations are executed one after another, without overlapping, like so:
$('#'+id).css({
top: newY,
left: newX
}).fadeIn(2000, function() {
setTimeout(function() {
$('#' + id).slideUp('fast');
window.cont = true;
}, 1500);
});
See working demo