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How to avoid "jumpy" UI updates?

I want to run simulations and update a progress bar, but the progress bar gets updated in a "jumpy" way. Eg. it moves from 21% to 34% to 76%. I'd like to to move one-by-one from 21% to 22% to 23% etc.
Consider this as a SSCCE:
http://embed.plnkr.co/XIKxpV6oWyWiwklFBSLh/
HTML
<button>Simulate</button>
JS
$(document).ready(function () {
var $button = $('button');
var worker = new Worker("worker.js");
worker.addEventListener("message", function(e) {
if (e.data) {
switch (e.data.cmd) {
case "progress":
$button.text((e.data.value / 250).toFixed(0) + "%");
break;
case "complete":
$button.text("Simulate");
break;
}
}
});
$button.on("click", function() {
worker.postMessage("start");
});
});
Worker
this.addEventListener("message", function(e) {
if (e.data === "start") {
for (var n = 0; n < 250000000; ++n) {
if (n % 10000 === 1) {
this.postMessage({cmd: "progress", value: n / 10000});
}
}
this.postMessage({cmd: "complete"});
}
});
How can I get it to update smoothly? Why isn't it updating smoothly to begin with?

You could change progress to provide fill values.
The reason why it's not smooth is that it doesn't post a progress value for all values, only every 10000 (if you try to post every value it's very likely your browser is going to freeze)
if (n % 10000 === 1) {
this.postMessage({cmd: "progress", value: n / 10000});
}
So you don't get all possible % values, you need to fill.
Something like this
$(document).ready(function () {
var $button = $('button');
var last = 0
var worker = new Worker("worker.js");
worker.addEventListener("message", function process(e) {
if (e.data) {
switch (e.data.cmd) {
case "progress":
var next = (e.data.value / 250)
var current = last
// fill values
// from last % to new %
for (; current < next; ++current) {
$button.text(current + "%")
}
last = current
$button.text(next.toFixed(0) + "%");
break;
case "complete":
$button.text("Simulate");
break;
}
}
});
$button.on("click", function() {
worker.postMessage("start");
});
});

Converting a manual slideshow to automatic

I followed a tutorial and created a simple manual loop slideshow. I'm trying to make it so it changes the slide automatically even if the prev/next buttons aren't clicked. I tried a crude approach by setting a delay between automatic click events on the "next" button but for some reason it clicks it only once and stops. My js knowledge is very limited and can't figure it out, any input is appreciated. This is the script so far:
$(function() {
var ul = $(".slider ul");
var slide_count = ul.children().length;
var slide_width_pc = 100.0 / slide_count;
var slide_index = 0;
var first_slide = ul.find("li:first-child");
var last_slide = ul.find("li:last-child");
last_slide.clone().prependTo(ul);
first_slide.clone().appendTo(ul);
ul.find("li").each(function(indx) {
var left_percent = (slide_width_pc * indx) + "%";
$(this).css({"left":left_percent});
$(this).css({width:(100 / slide_count) + "%"});
});
ul.css("margin-left", "-100%");
$(".slider .prev").click(function() {
console.log("prev button clicked");
slide(slide_index - 1);
});
$(".slider .next").click(function() {
console.log("next button clicked");
slide(slide_index + 1);
});
function slide(new_slide_index) {
var margin_left_pc = (new_slide_index * (-100) - 100) + "%";
ul.animate({"margin-left": margin_left_pc}, 400, function() {
if(new_slide_index < 0) {
ul.css("margin-left", ((slide_count) * (-100)) + "%");
new_slide_index = slide_count - 1;
}
else if(new_slide_index >= slide_count) {
ul.css("margin-left", "-100%");
new_slide_index = 0;
}
slide_index = new_slide_index
});
}
});

Here is an approach to make it sliding automatically...
But if user clicks on prev/next, it holds the automatic feature for a defined "idle" time.
It need two lines added to your click handlers:
var autoEnabled = true; // ADDED
$(".slider .prev").click(function() {
console.log("prev button clicked");
slide(slide_index - 1);
autoEnabled = false; // ADDED
disabledCount = 0; // ADDED
});
$(".slider .next").click(function() {
console.log("next button clicked");
slide(slide_index + 1);
autoEnabled = false; // ADDED
disabledCount = 0; // ADDED
});
And this to cyclically slide or check if it can re-enable itself.
// ----------------- Automatic sliding interval with "idle time" to re-enable on user click
var idleTime = 5000; // Time without manual click to re-enable automatic sliding.
var autoSlideDelay = 1000; // Time between each slide when automatic.
var disabledCount = 0;
var autoSlide = setInterval(function(){
if(autoEnabled || disabledCount >= idleTime/autoSlideDelay ){
disabledCount = 0;
autoEnabled = true;
slide(slide_index + 1);
}else{
disabledCount++;
}
},autoSlideDelay);

var break_auto_slide = false;
function auto_silde()
{
if(break_auto_slide)
{
break_auto_slide = false;
return;
}
slide(slide_index + 1);
setTimeout(auto_silde,1000 /* time in ms*/);
}
setTimeout will call the function in a specified timeout in milliseconds.
Variable break_auto_slide - set it to true to stop the automatic slide. Next time the function is called it will return without setting a new timer and will reset this variable so auto mode can be turned on again.

scroll other scrollbars with scrollbar

i have 3 divs with scrollbars.
If i scroll in div 1 i want to scroll div 2 and 3 in the opposite direction.
The distance scrolled should be half the distance of div 1.
This is what i have now (small part, rest is in jsfiddle), which works for 1 div.
$("#textBox1").scroll(function () {
console.log("scroll 1");
var offset = $("#textBox1").scrollTop() - scrollPosTBox1;
var half_offset = offset/2.0;
disable1 = true;
if(disable2 == false) {
$("#textBox2").scrollTop(scrollPosTBox2 - half_offset);
}
if(disable3 == false) {
$("#textBox3").scrollTop(scrollPosTBox3 - half_offset);
}
disable1 = false;
});
However, if i try to get the same for the other 2 divs then i can't scroll anything anymore.
This is because div 1 triggers div 2 and div 2 triggers back to div 1 for example.
I tried to fix this with the disable code but it doesn't help.
Can someone help me?
http://jsfiddle.net/XmYh5/1/

No disrespect to #EmreErkan and #Simon for their effort. Here's a no-click version of this.
var $boxes = $("#textBox1,#textBox2,#textBox3"),
active;
$boxes.scrollTop(150);
// set initial scrollTop values
updateScrollPos();
// bind mouseenter:
// 1) find which panel is active
// 2) update scrollTop values
$boxes.mouseenter(function () {
active = this.id;
updateScrollPos();
});
// bind scroll for all boxes
$boxes.scroll(function (e) {
$this = $(this);
// check to see if we are dealing with the active box
// if true then set scrolltop of other boxes relative to the active box
if(this.id == active){
var $others = $boxes.not($this),
offset = $this.scrollTop()-$this.data("scroll"),
half_offset = offset / 2;
$others.each(function(){
$this = $(this);
$this.scrollTop($this.data("scroll") - half_offset);
});
}
});
// utility function:
// assign scrollTop values element's data attributes (data-scroll)
function updateScrollPos() {
$boxes.each(function(){
$this = $(this);
$this.data("scroll",$this.scrollTop());
});
}
Fiddle

You can use a variable to determine active textbox with .mousedown() and do the trick if it's active;
var activeScroll = '';
$("#textBox1").on('mousedown focus mouseenter', function () {
activeScroll = 'scroll1';
}).scroll(function () {
if (activeScroll == 'scroll1') {
console.log("scroll 1");
var offset = $("#textBox1").scrollTop() - scrollPosTBox1;
var half_offset = offset / 2.0;
$("#textBox2").scrollTop(scrollPosTBox2 - half_offset);
$("#textBox3").scrollTop(scrollPosTBox3 - half_offset);
}
});
You can check your updated jsFiddle here.

Finally got a dynamic solution for this, was more complex than I thought but I think I got it:
http://jsfiddle.net/XmYh5/14/
var initialTop = 150,
factor = 2;
$(".textBox")
.addClass('disabled')
.scrollTop(initialTop)
.on('scroll', function () {
var $this = $(this);
if(!$this.is('.disabled')) {
this.lastOffset = this.lastOffset || initialTop;
var offset = $this.scrollTop(),
step = (offset - this.lastOffset) / factor;
$this.siblings().each( function() {
var $this = $(this),
offset = $this.scrollTop() - step;
$this.scrollTop(offset);
this.lastOffset = offset;
});
this.lastOffset = offset;
}
})
.on('mouseenter', function() {
$(this).removeClass('disabled').siblings().addClass('disabled');
});

Jquery slideshow starts with an image on the left of a row but I want it to start at the right end

I'm using this javascript and the slide show slides right to left with the images in this order and positon:
start postion > 1 | 2 | 3 | 4 | 5 | 6 etc etc
but I want to swap them so they run in this position
6 | 5 | 4 | 3 | 2 | 1 < start position
Kind of like reading a book back to front, but keeping it in the right order
I've been told I need to modify the lines labelled below: //MODIFY ME
I hope someone can help! Thank you
Here's my code
(function($) {
$.fn.slideshow = function(method) {
if ( this[0][method] ) {
return this[0][ method ].apply( this, Array.prototype.slice.call( arguments, 1 ));
} else if ( typeof method === 'object' || ! method ) {
return this.each(function() {
var ANIMATION_DURATION = .6; // The duration to flick the content. In seconds.
var MOVE_THRESHOLD = 10; // Since touch points can move slightly when initiating a click this is the
// amount to move before allowing the element to dispatch a click event.
var itemWidth;
var horizontalGap;
var $this = $(this);
var collection;
var viewItems = [];
var touchStartTransformX; // The start transformX when the user taps.
var touchStartX; // The start x coord when the user taps.
var interval; // Interval used for measuring the drag speed.
var wasContentDragged; // Flag for whether or not the content was dragged. Takes into account MOVE_THRESHOLD.
var targetTransformX; // The target transform X when a user flicks the content.
var touchDragCoords = []; // Used to keep track of the touch coordinates when dragging to measure speed.
var touchstartTarget; // The element which triggered the touchstart.
var selectedIndex = 0; // The current visible page.
var viewPortWidth; // The width of the div that holds the horizontal content.
var isAnimating;
var pageChangedLeft;
// The x coord when the items are reset.
var resetX;
var delayTimeout;
init(method);
function init(options) {
collection = options.data;
renderer = options.renderer;
itemWidth = options.itemWidth;
horizontalGap = options.horizontalGap;
initLayout();
$this[0].addEventListener("touchstart", touchstartHandler);
$this[0].addEventListener("mousedown", touchstartHandler);
viewPortWidth = $this.width();
$this.on("webkitTransitionEnd", transitionEndHandler);
collection.on("add", addItem);
}
// MODIFY ME
function initLayout() {
// Layout five items. The one in the middle is always the selected one.
for (var i = 0; i < 5; i++) {
var viewItem;
if (i > 1 && collection.at(i - 2)) // Start at the one in the middle. Subtract 2 so data index starts at 0.
viewItem = new renderer({model: collection.at(i - 2)});
else
viewItem = new renderer();
viewItem.render().$el.appendTo($this);
viewItem.$el.css("left", itemWidth * i + horizontalGap * i);
viewItem.setState(i != 2 ? "off" : "on");
viewItems.push(viewItem);
}
// Center the first viewItem
resetX = itemWidth * 2 - ($this.width() - itemWidth - horizontalGap * 4) / 2;
setTransformX(-resetX);
}
function getCssLeft($el) {
var left = $el.css("left");
return Number(left.split("px")[0]);
}
// MODIFY ME
function transitionEndHandler() {
if (pageChangedLeft != undefined) {
var viewItem;
if (pageChangedLeft) {
// Move the first item to the end.
viewItem = viewItems.shift();
viewItems.push(viewItem);
viewItem.model = collection.at(selectedIndex + 2);
viewItem.$el.css("left", getCssLeft(viewItems[3].$el) + itemWidth + horizontalGap);
} else {
// Move the last item to the beginning.
viewItem = viewItems.pop();
viewItems.splice(0, 0, viewItem);
viewItem.model = collection.at(selectedIndex - 2);
viewItem.$el.css("left", getCssLeft(viewItems[1].$el) - itemWidth - horizontalGap);
}
viewItem.render();
// Reset the layout of the items.
for (var i = 0; i < 5; i++) {
var viewItem = viewItems[i];
viewItem.$el.css("left", itemWidth * i + horizontalGap * i);
viewItem.setState(i != 2 ? "off" : "on");
}
// Reset the transformX so we don't run into any rendering limits. Can't find a definitive answer for what the limits are.
$this.css("-webkit-transition", "none");
setTransformX(-resetX);
pageChangedLeft = undefined;
}
}
function touchstartHandler(e) {
clearInterval(interval);
wasContentDragged = false;
transitionEndHandler();
// Prevent the default so the window doesn't scroll and links don't open immediately.
e.preventDefault();
// Get a reference to the element which triggered the touchstart.
touchstartTarget = e.target;
// Check for device. If not then testing on desktop.
touchStartX = window.Touch ? e.touches[0].clientX : e.clientX;
// Get the current transformX before the transition is removed.
touchStartTransformX = getTransformX();
// Set the transformX before the animation is stopped otherwise the animation will go to the end coord
// instead of stopping at its current location which is where the drag should begin from.
setTransformX(touchStartTransformX);
// Remove the transition so the content doesn't tween to the spot being dragged. This also moves the animation to the end.
$this.css("-webkit-transition", "none");
// Create an interval to monitor how fast the user is dragging.
interval = setInterval(measureDragSpeed, 20);
document.addEventListener("touchmove", touchmoveHandler);
document.addEventListener("touchend", touchendHandler);
document.addEventListener("mousemove", touchmoveHandler);
document.addEventListener("mouseup", touchendHandler);
}
function measureDragSpeed() {
touchDragCoords.push(getTransformX());
}
function touchmoveHandler(e) {
var deltaX = (window.Touch ? e.touches[0].clientX : e.clientX) - touchStartX;
if (wasContentDragged || Math.abs(deltaX) > MOVE_THRESHOLD) { // Keep track of whether or not the user dragged.
wasContentDragged = true;
setTransformX(touchStartTransformX + deltaX);
}
}
function touchendHandler(e) {
document.removeEventListener("touchmove", touchmoveHandler);
document.removeEventListener("touchend", touchendHandler);
document.removeEventListener("mousemove", touchmoveHandler);
document.removeEventListener("mouseup", touchendHandler);
clearInterval(interval);
e.preventDefault();
if (wasContentDragged) { // User dragged more than MOVE_THRESHOLD so transition the content.
var previousX = getTransformX();
var bSwitchPages;
// Compare the last 5 coordinates
for (var i = touchDragCoords.length - 1; i > Math.max(touchDragCoords.length - 5, 0); i--) {
if (touchDragCoords[i] != previousX) {
bSwitchPages = true;
break;
}
}
// User dragged more than halfway across the screen.
if (!bSwitchPages && Math.abs(touchStartTransformX - getTransformX()) > (viewPortWidth / 2))
bSwitchPages = true;
if (bSwitchPages) {
if (previousX > touchStartTransformX) { // User dragged to the right. go to previous page.
if (selectedIndex > 0) { // Make sure user is not on the first page otherwise stay on the same page.
selectedIndex--;
tweenTo(touchStartTransformX + itemWidth + horizontalGap);
pageChangedLeft = false;
} else {
tweenTo(touchStartTransformX);
pageChangedLeft = undefined;
}
} else { // User dragged to the left. go to next page.
if (selectedIndex + 1 < collection.length) {// Make sure user is not on the last page otherwise stay on the same page.
selectedIndex++;
tweenTo(touchStartTransformX - itemWidth - horizontalGap);
pageChangedLeft = true;
} else {
tweenTo(touchStartTransformX);
pageChangedLeft = undefined;
}
}
} else {
tweenTo(touchStartTransformX);
pageChangedLeft = undefined;
}
} else { // User dragged less than MOVE_THRESHOLD trigger a click event.
var event = document.createEvent("MouseEvents");
event.initEvent("click", true, true);
touchstartTarget.dispatchEvent(event);
}
}
// Returns the x of the transform matrix.
function getTransformX() {
var transformArray = $this.css("-webkit-transform").split(","); // matrix(1, 0, 0, 1, 0, 0)
var transformElement = $.trim(transformArray[4]); // remove the leading whitespace.
return transformX = Number(transformElement); // Remove the ).
}
// Sets the x of the transform matrix.
function setTransformX(value) {
$this.css("-webkit-transform", "translateX("+ Math.round(value) + "px)");
}
function tweenTo(value) {
isAnimating = true;
targetTransformX = value;
// Set the style for the transition.
$this.css("-webkit-transition", "-webkit-transform " + ANIMATION_DURATION + "s");
// Need to set the timing function each time -webkit-transition is set.
// The transition is set to ease-out.
$this.css("-webkit-transition-timing-function", "cubic-bezier(0, 0, 0, 1)");
setTransformX(targetTransformX);
}
// MODIFY ME
function addItem(folio) {
clearTimeout(delayTimeout);
// Create a timeout in case multiple items are added in the same frame.
// When the timeout completes all of the view items will have their model
// updated. The renderer should check to make sure the model is different
// before making any changes.
delayTimeout = setTimeout(function(folio) {
var index = collection.models.indexOf(folio);
var dataIndex = index;
var firstIndex = selectedIndex - 2;
var dataIndex = firstIndex;
var viewItem;
for (var i = 0; i < viewItems.length; i++) {
viewItem = viewItems[i];
if (dataIndex >= 0 && dataIndex < collection.length) {
viewItem.model = collection.at(dataIndex);
viewItem.render();
}
viewItem.setState(i != 2 ? "off" : "on");
dataIndex += 1;
}
}, 200);
}
// Called when the data source has changed. Resets the view with the new data source.
this.setData = function(data) {
$this.empty();
viewItems = [];
collection = data;
selectedIndex = 0;
initLayout();
}
});
} else {
$.error( 'Method ' + method + ' does not exist on Slideshow' );
}
}
})(jQuery);

From what I can make out, you need to simply "flip" the loops that create the sides in the slideshow so that it makes the last slide where it was making the first. It seems to do this in two places.
Then, you will need to amend the code which adds a slide to make it add it before the other slides instead of after.
This sounds an awful lot like homework - it's always best to attempt an answer before asking on here. An example on a site like JSFiddle is also generally appreciated.

.next() not working as intended

So,
if($(this).hasClass('active')){
$(this).removeClass('active');
$(this).prev().addClass('active');
}
works fine, it adds the class "active" to this previous div of the same kind.
if($(this).hasClass('active')){
$(this).removeClass('active');
$(this).next().addClass('active');
}
However, adds the class to the next div (as i intend for it to do) for about 0.5 of a second BUT then removes it.
Here's ALL of the jQuery (as per your comments below) - Please do not comment on my horrible code organization
$(window).load(function () {
// Initial variables
var numberSlides = 0;
var currentSlide = 1;
var ready = true;
var pageWidthR = $(document).width() - 352;
var pageWidthL = $(document).width() - 352;
// Update number of slides by number of .slide elements
$('#features-slider .slide').each(function () {
numberSlides++;
});
// Go through each slide and move it to the left of the screen
var i = 0;
$($('#features-slider .slide').get().reverse()).each(function () {
if (i == 0) {
} else {
var newWidth = i * 115;
$(this).css('left', '-' + newWidth + '%');
}
i++;
});
// Animate the first slide in
$('#features-slider .slide:last-child').addClass('active').animate({
left: 0
}, 1500);
// Remove the loading message
$('#loading').fadeOut(1000, function () {
$('#loading').remove();
// Now that we're done - we can show it
$('#features-slider').show();
});
/***** Left and Right buttons *****/
/* Right */
$('#rightbutton').click(function () {
var numberSlides = 0;
$('#features-slider .slide').each(function () {
numberSlides++;
});
var index = $('.slide.active').index() + 1;
if (!$('.slide').is(':animated') && index != 1) {
$('#features-slider .slide').each(function () {
if ($(this).hasClass('active')) {
var currentLeft = $(this).css('left');
var newLeft = parseInt(currentLeft) + 115;
} else {
var currentLeft = $(this).css('left');
var newLeft = parseInt(currentLeft) + 115;
}
$(this).animate({
left: newLeft + '%'
}, 1500);
if ($(this).hasClass('active')) {
$(this).removeClass('active');
$(this).prev().addClass('active');
}
});
}
});
/* Left */
$('#leftbutton').click(function () {
var numberSlides = 0;
$('#features-slider .slide').each(function () {
numberSlides++;
});
var index = $('.slide.active').index() + 1;
if (!$('.slide').is(':animated') && index != numberSlides) {
$('#features-slider .slide').each(function () {
if ($(this).hasClass('active')) {
var currentLeft = $(this).css('left');
var newLeft = parseInt(currentLeft) - 115;
} else {
var currentLeft = $(this).css('left');
var newLeft = parseInt(currentLeft) - 115;
}
$(this).animate({
left: newLeft + '%'
}, 1500);
if ($(this).hasClass('active')) {
$(this).next().addClass('active');
$(this).removeClass('active').not($(this).next());
}
});
}
});
});
$(document).ready(function () {
// Hide the slider and show a loading message while we do stuff and the images / DOM loads - Also disable overflow on the body so no horizontal scrollbar is shown
$('body').css('overflow-x', 'hidden');
$('#features-slider').hide();
$('#loading').html('<center> <img id="loader" src="/wp-content/themes/responsive/library/images/ajax-loader.gif" /> Loading</center>');
});
RESOLVED
New left button function :
$('#leftbutton').click(function(){
var numberSlides = 0;
$('#features-slider .slide').each(function(){
numberSlides++;
});
var index = $('.slide.active').index()+1;
if( !$('.slide').is(':animated') && index != numberSlides ){
var done = false;
$('#features-slider .slide').each(function(){
if($(this).hasClass('active')){
var currentLeft = $(this).css('left');
var newLeft = parseInt(currentLeft)-115;
} else {
var currentLeft = $(this).css('left');
var newLeft = parseInt(currentLeft)-115;
}
$(this).animate({left: newLeft+'%'}, 1500);
if($(this).hasClass('active') && done == false){
$(this).next().addClass('active');
$(this).removeClass('active');
done = true;
}
});
});

If you're iterating forward through the elements, then it should be clear what's going on - you add the "active" class to the next element, and then the next iteration takes it away.
This is just a guess however as you did not post enough code for me (or anybody else) to be sure.
edit — ok now that you've updated the question, it's clear that the guess was correct. The .each() function will iterate forward through the elements. When an element has the "active" class, and the code removes it and adds it to the next element, then on the next iteration the work is undone.

Since you are referencing this and by the behavior you're describing, you are likely iterating a loop for a list of elements. As a result, you are completing the action you want but the next iteration is removing the previous changes due to your usage of removing a class and then adding the class back.
As it stands now, your code does not illustrate how this occurence can be happening.
Update:
As suspected, you seem to be looping as signified by: each(function(){. While iterating through your objects the class is being pushed forward and is not acting as desired. You are stating add the class to the next element, but remove it from the current element, and this behavior continues through your iteration.
On a side note, update your code to call removeClass() on the current object first, before adding it to the next object:
if ($(this).hasClass('active')) {
$(this).removeClass('active').next().addClass('active');
}