Develop Reference

Trying to get this smoother and more natural in behavior

My implementation,
http://kodhus.com/kodnest/land/PpNFTgp
I am curious, as I am not able for some reason to figure this out, how to get my JavaScript to make my slider behave more natural and smoother, if someone knows, how to, or can make this, feel free. I'd be happy to understand.
JavaScript:
const thumb = document.querySelector('.thumb');
const thumbIndicator = document.querySelector('.thumb .thumb-indicator');
const sliderContainer = document.querySelector('.slider-container');
const trackProgress = document.querySelector('.track-progress');
const sliderContainerStart = sliderContainer.offsetLeft;
const sliderContainerWidth = sliderContainer.offsetWidth;
var translate;
var dragging = false;
var percentage = 14;
document.addEventListener('mousedown', function(e) {
if (e.target.classList.contains('thumb-indicator')) {
dragging = true;
thumbIndicator.classList.add('focus');
}
});
document.addEventListener('mousemove', function(e) {
if (dragging) {
console.log('moving', e)
if (e.clientX < sliderContainerStart) {
translate = 0;
} else if (e.clientX > sliderContainerWidth + sliderContainerStart) {
translate = sliderContainerWidth;
} else {
translate = e.clientX - sliderContainer.offsetLeft;
}
thumb.style.transform = 'translate(-50%) translate(' + translate + 'px)';
trackProgress.style.transform = 'scaleX(' + translate / sliderContainerWidth + ')'
}
});
function setPercentage() {
thumb.style.transform = 'translate(-50%) translate(' + percentage/100 * sliderContainerWidth + 'px)';
trackProgress.style.transform = 'scaleX(' + percentage/100 + ')';
}
function init() {
setPercentage();
}
init();
document.addEventListener('mouseup', function(e) {
dragging = false;
thumbIndicator.classList.remove('focus');
});
EDIT: Is there a way to smoothly and naturally increment by one for every slow move?
Is it possible to make to behave as if, like when one clicks the progress bar so that it jumps there?

The kodhus site is very janky in my browser, so I can't tell if your code lacks responsiveness or whether it's the site itself. I feel that your code is a bit convoluted: translate and width / height are mixed unnecessarily; no need to use a dragging boolean when that information is always stored in the classlist. The following slider performs nicely, and has a few considerations I don't see in yours:
stopPropagation when clicking the .thumb element
drag stops if window loses focus
pointer-events: none; applied to every part of the slider but the .thumb element
let applySliderFeel = (slider, valueChangeCallback=()=>{}) => {
// Now `thumb`, `bar` and `slider` are the elements that concern us
let [ thumb, bar ] = [ '.thumb', '.bar' ].map(v => slider.querySelector(v));
let changed = amt => {
thumb.style.left = `${amt * 100}%`;
bar.style.width = `${amt * 100}%`;
valueChangeCallback(amt);
};
// Pressing down on `thumb` activates dragging
thumb.addEventListener('mousedown', evt => {
thumb.classList.add('active');
evt.preventDefault();
evt.stopPropagation();
});
// Releasing the mouse button (anywhere) deactivates dragging
document.addEventListener('mouseup', evt => thumb.classList.remove('active'));
// If the window loses focus dragging also stops - this can be a very
// nice quality of life improvement!
window.addEventListener('blur', evt => thumb.classList.remove('active'));
// Now we have to act when the mouse moves...
document.addEventListener('mousemove', evt => {
// If the drag isn't active do nothing!
if (!thumb.classList.contains('active')) return;
// Compute `xRelSlider`, which is the mouse position relative to the
// left side of the slider bar. Note that *client*X is compatible with
// getBounding*Client*Rect, and using these two values we can quickly
// get the relative x position.
let { width, left } = slider.getBoundingClientRect();
// Consider mouse x, subtract left offset of slider, and subtract half
// the width of the thumb (so drags position the center of the thumb,
// not its left side):
let xRelSlider = evt.clientX - left - (thumb.getBoundingClientRect().width >> 1);
// Clamp `xRelSlider` between 0 and the slider's width
if (xRelSlider < 0) xRelSlider = 0;
if (xRelSlider > width) xRelSlider = width;
// Apply styling (using percents is more robust!)
changed(xRelSlider / width);
evt.preventDefault();
evt.stopPropagation();
});
slider.addEventListener('mousedown', evt => {
let { width, left } = slider.getBoundingClientRect();
// Clicking the slider also activates a drag
thumb.classList.add('active');
// Consider mouse x, subtract left offset of slider, and subtract half
// the width of the thumb (so drags position the center of the thumb,
// not its left side):
let xRelSlider = evt.clientX - left - (thumb.getBoundingClientRect().width >> 1);
// Apply styling (using percents is more robust!)
changed(xRelSlider / width);
evt.preventDefault();
evt.stopPropagation();
});
changed(0);
};
let valElem = document.querySelector('.value');
applySliderFeel(document.querySelector('.slider'), amt => valElem.innerHTML = amt.toFixed(3));
.slider {
position: absolute;
width: 80%; height: 4px; background-color: rgba(0, 0, 0, 0.3);
left: 10%; top: 50%; margin-top: -2px;
}
.slider > .bar {
position: absolute;
left: 0; top: 0; width: 0; height: 100%;
background-color: #000;
pointer-events: none;
}
.slider > .thumb {
position: absolute;
width: 20px; height: 20px; background-color: #000; border-radius: 100%;
left: 0; top: 50%; margin-top: -10px;
}
.slider > .thumb.active {
box-shadow: 0 0 0 5px rgba(0, 0, 0, 0.5);
}
<div class="slider">
<div class="bar"></div>
<div class="thumb"></div>
</div>
<div class="value"></div>

How do I make a progress bar?

I'm trying to create a progress bar for a product card track so by any click of the user on the prev and next buttons (which would scroll back or forward) the progress bar would advance or backup.
here's the code I came up with. the problem is the first click doesn't show any result and the prev button acts like the next button for the first time. It's like the code is one step behind.
I'm very new to javaScript and I can't figure out how this could happen.
const productScroll = () => {
rightButton.onclick = function () {
let scrollLeft = document.querySelector('#ProductSlider').scrollLeft;
let scrollPercent = ((scrollLeft - 0) / (5033 - 0)) * (100 - 0) + 0;
document.querySelector('div.progress-bar').style.width = `${scrollPercent}%`;
};
leftButton.onclick = function () {
let scrollLeft = document.querySelector('#ProductSlider').scrollLeft;
let scrollPercent = ((scrollLeft - 0) / (5033 - 0)) * (100 - 0) + 0;
document.querySelector('div.progress-bar').style.width = `${scrollPercent}%`;
};

If youre always 1 step behind, it could be that your percentage calculation is wrong. For example, if you have 5 steps and want to show progress for each step, starting at 1 and ending at 5, your progress bar needs to have 4 steps instead:
1 > 2 > 3 > 4 > 5 = 4 steps (total - 1)
In percentages, it looks like this for a 5 step progress bar:
1: 0%
2: 25%
3: 50%
4: 75%
5: 100%
Notice each increase is 25% (1/4) and not 20% (1/5).
So in abstract shape, your calculation would need to be:
((scroll / max) * (steps - 1)) / (steps - 1) * 100%
Which means your scrollLeft / 5033 needs to be between 0 and 4, divided by 4, then turned into a percentage:
const percentage = ((scrollLeft / 5033) * 4) / 4 * 100;

To create a progress bar, first create two “div” tag elements named id Progress_Status and myprogressbar.
To add a numeric label to indicate how far the user is in the process, the element inside or outside the progress bar is required which will display the progress status which in this case is myprogressbar.
<div id="Progress_Status">
<div id="myprogressBar">1%</div>
</div>
Adding CSS:
#Progress_Status {
width: 50%;
background-color: #ddd;
}
#myprogressBar {
width: 1%;
height: 35px;
background-color: #4CAF50;
text-align: center;
line-height: 32px;
color: black;
}
Adding JavaScript:
Next, Code below creates a dynamic progress bar(animated) using JavaScript functions update and scene.
function update() {
var element = document.getElementById("myprogressBar");
var width = 1;
var identity = setInterval(scene, 10);
function scene() {
if (width >= 100) {
clearInterval(identity);
} else {
width++;
element.style.width = width + '%';
element.innerHTML = width * 1 + '%';
}
}
}
Firstly, you fetch the element by id and then set starting width to 1. For the purpose of working example, i used setintervel to show the progression of progress bar.
All we are doing here is calling the scene function which checks if width is less than 100. If yes, then stop loader by clearing the interval. If not, then increment the width and add it to the with and progress label div for showing the progress in percentenge.
Complete Code:
function update() {
var element = document.getElementById("myprogressBar");
var width = 1;
var identity = setInterval(scene, 10);
function scene() {
if (width >= 100) {
clearInterval(identity);
} else {
width++;
element.style.width = width + '%';
element.innerHTML = width * 1 + '%';
}
}
}
#Progress_Status {
width: 50%;
background-color: #ddd;
}
#myprogressBar {
width: 1%;
height: 35px;
background-color: #4CAF50;
text-align: center;
line-height: 32px;
color: black;
}
<!DOCTYPE html>
<html>
<body>
<h3>Example of Progress Bar Using JavaScript</h3>
<p>Download Status of a File:</p>
<div id="Progress_Status">
<div id="myprogressBar">1%</div>
</div>
<br>
<button onclick="update()">Start Download</button>
</body>
</html>

HTMLElement.offsetTop doesn't work in subpixel precision

I am writing a small program where I move DOMs at a specified speed.
When I move it at the rate of 20px per second, the offset that gets added to the elem.style.top is about 0.3px per frame.
The problem is, when this offset is smaller than 0.5px, elem doesn't move!
I constructed a simplified example that can demonstrate the issue in my program:
var requestFrameAnimationId;
function myMove(offset) {
var elem = document.getElementById("animate");
requestFrameAnimationId = animationLoop(frame);
function frame() {
console.log(elem.offsetTop);
if (elem.offsetTop === 350) {
cancelAnimationFrame(requestFrameAnimationId);
} else {
elem.style.top = elem.offsetTop + offset + 'px';
elem.style.left = elem.offsetLeft + offset + 'px';
}
}
}
function animationLoop(render) {
var running, lastFrame = +new Date(); // casting Date to Number
function loop(now) {`enter code here`
requestFrameAnimationId = requestAnimationFrame(loop);
running = render(now - lastFrame);
lastFrame = now;
}
loop(lastFrame);
}
#container {
width: 400px;
height: 400px;
position: relative;
background: yellow;
}
#animate {
width: 50px;
height: 50px;
position: absolute;
background-color: red;
}
<!DOCTYPE html>
<html>
<body>
<p>
<button onclick="myMove(0.3)">Move at 0.3px per frame</button>
<button onclick="myMove(0.5)">Move at 0.5px per frame</button>
</p>
<div id="container">
<div id="animate"></div>
</div>
</body>
</html>
Try clicking on Move at 0.5px per frame. The rectangle should be moving.
Reset it by clicking on Run code snippet.
Now try clicking on Move at 0.3px per frame.
It should be moving the DOM more slowly, but you can see that the DOM is not moving.
It's strange because when I initially kept track of the top position in a javascript variable topPos, and applied ${topPos + offset} to elem.style.top, it worked at even slower speeds!
So my guess is that elem.offsetTop rounds the decimal values, so 0.3 becomes 0, and 0.5 becomes 1.
What can I do to make it so that the DOM moves precisely at the specified speed? I can't use any libraries for this one.
EDIT: I looked more into the problem and I believe it's offsetTop that rounds the numbers to integers.
However, I found out that CSS OM spec changed the type of offsetTop to float, and the Chromium team was working on applying the change on the browser more than 4 years ago, and it seems that it should be fixed by now.
Why is it not working on my program, and how can I make it work?
EDIT2: I found from CSSOM working draft that the type of offsetTop was integer.
readonly attribute long offsetTop;
I think they only changed the type of scrollTop and scrollLeft to a double precision number.
attribute unrestricted double scrollTop;
attribute unrestricted double scrollLeft;

HTMLElement.offset[Left | Top] return long typed value (i.e integer).
Use Element.getBoundingClientRect if you want float values.
var requestFrameAnimationId;
function myMove(offset) {
var elem = document.getElementById("animate");
requestFrameAnimationId = animationLoop(frame);
function frame() {
// build up our own high precision offsetTop
var parentRect = elem.offsetParent && elem.offsetParent.getBoundingClientRect() || {top: 0, left:0};
var elemRect = elem.getBoundingClientRect();
var rect = {
top: elemRect.top - parentRect.top,
left: elemRect.left - parentRect.left
};
if (rect.top >= 350) {
cancelAnimationFrame(requestFrameAnimationId);
} else {
// so we can substract it here
elem.style.top = (rect.top + offset) + 'px';
elem.style.left = (rect.left + offset) + 'px';
}
}
}
function animationLoop(render) {
var running, lastFrame = +new Date(); // casting Date to Number
function loop(now) {
requestFrameAnimationId = requestAnimationFrame(loop);
running = render(now - lastFrame);
lastFrame = now;
}
loop(lastFrame);
}
#container {
width: 400px;
height: 400px;
position: relative;
background: yellow;
}
#animate {
width: 50px;
height: 50px;
position: absolute;
background-color: red;
}
<p>
<button onclick="myMove(0.3)">Move at 0.3px per frame</button>
<button onclick="myMove(0.5)">Move at 0.5px per frame</button>
</p>
<div id="container">
<div id="animate"></div>
</div>
Or simply add up your values to a variable:
var requestFrameAnimationId;
function myMove(offset) {
var elem = document.getElementById("animate");
requestFrameAnimationId = animationLoop(frame);
var pos = 0;
function frame() {
pos += offset;
if (pos >= 350) {
cancelAnimationFrame(requestFrameAnimationId);
} else {
elem.style.top = pos + 'px';
elem.style.left = pos + 'px';
}
}
}
function animationLoop(render) {
var running, lastFrame = +new Date(); // casting Date to Number
function loop(now) {
requestFrameAnimationId = requestAnimationFrame(loop);
running = render(now - lastFrame);
lastFrame = now;
}
loop(lastFrame);
}
#container {
width: 400px;
height: 400px;
position: relative;
background: yellow;
}
#animate {
width: 50px;
height: 50px;
position: absolute;
background-color: red;
}
<p>
<button onclick="myMove(0.3)">Move at 0.3px per frame</button>
<button onclick="myMove(0.5)">Move at 0.5px per frame</button>
</p>
<div id="container">
<div id="animate"></div>
</div>

slide image from left to right and reverse back again

I am trying to slide image from left to right and after a set point it should again slide in reverse direction. This is my code somehow its not working as i am going wrong somewhere in the if statement.
(function($) {
var x = 0;
var y = 0;
//cache a reference to the banner
var banner = $("#banner");
// set initial banner background position
banner.css('backgroundPosition', x + 'px' + ' ' + y + 'px');
// scroll up background position every 90 milliseconds
window.setInterval(function() {
banner.css("backgroundPosition", x + 'px' + ' ' + y + 'px');
x++;
//x--;
//if you need to scroll image horizontally -
// uncomment x and comment y
}, 90);
if ($(banner.offset().left > 40) {
banner.css("backgroundPosition", "0px 0px ");
}
})(jQuery);
div#banner {
width: 960px;
height: 200px;
margin: auto;
background: url(http://cdn-careers.sstatic.net/careers/gethired/img/companypageadfallback-leaderboard-2.png?v=59b591051ad7) no-repeat 0 0;
}
div#banner p {
font: 15px Arial, Helvetica, sans-serif;
color: white;
position: relative;
left: 20px;
top: 120px;
width: 305px;
padding: 20px;
background: black;
text-align: center;
text-transform: uppercase;
letter-spacing: 20px;
zoom: 1;
filter: alpha(opacity=50);
opacity: 0.5;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="banner"></div>

Firstly, you are using a IIFE (Immediately Invoked Function Expression) instead of a DOM ready handler. This code will only work if placed after the elements it references.
Use this shortcut for DOM ready that also provides a locally scoped $
jQuery(function ($) {...});
You also have a missing closing paren (or really a redundant $( as it is already a jQuery object):
JSFiddle: http://jsfiddle.net/g0gn4osy/7/
You also need to have a delta value that changes the direction when you hit a bound value. I sped up your timing to show this:
jQuery(function ($) {
var delta = 1;
var y = 0;
//cache a reference to the banner
var $banner = $("#banner");
// set initial banner background position
$banner.css('background-position', '0px' + ' ' + y + 'px');
// scroll up background position every 90 milliseconds
window.setInterval(function () {
var position = parseInt($banner.css('background-position'));
if (position >= 40 || position < 0) {
delta = -delta;
}
position += delta;
$banner.css("background-position", position + 'px' + ' ' + y + 'px');
}, 10);
});
Notes:
You also had backgroundPosition instead of background-position for the CSS property. I prefer to use the values that match the css properties (personal choice only for maintenance).
To avoid the redundant $() issue, I recommend you prefix jQuery variables with $. e.g. $banner in this case. Then it becomes obvious you are dealing with a jQuery object.
I tend to use the current position of an element, rather than keep a global var running. This allows for external influences to change the position and still work. Have removed x and just use position.

Inspired and modelled on Gone Coding's answer.
I have expanded his example to take into account the image width and the view pane DIV width.
It now scrolls to image end and then back. You never scroll off the canvas or past a visible part of the image. It doesn't jerk or rock, just switches direction.
With awareness of the viewing box width you can easily adjust the width of div#banner to fit the display space and the code adjusts. Just remember to set the background image width imgW var.
I have also added:
Visual indicator for testing with a current position and scroll direction. (With -1 is scrolling left, +1 is scrolling right),
Image start position in px. (A minus number or Zero. With 0 is start image at left, Minus number is start image part way through i.e image pre-scrolled left)
Image start vertical position in px (to vertically pull image up/down. Useful if view pane height shorter than image height and you want to tweak what is seen)
Things to do:
Change image URL (background: url(IMAGENAMEHERE) no-repeat 0 0;)
Insert image width (var imgW = #PIXELWIDTH#;)
Play with WIDTH: and HEIGHT: of view pane (div#banner)
Enjoy.
Fiddle
Have a play http://jsfiddle.net/Lm5yk46h/
Image credit Mark Higgins | Dreamstime.com Image source for purchase
Javascript
jQuery(function ($) {
var delta = 1;
var imgW = 3000;//width of image px
var imgY = 0;//to shift image view vertically px (Minus or zero)
//cache ref to #banner
var $banner = $("#banner");
var viewpaneW = $banner.width();
var endpos = (imgW - viewpaneW);
var startpos = 0;//0 or negative number
// set initial banner background position
$banner.css('background-position', startpos + 'px' + ' ' + imgY + 'px');
// scroll background position every 20ms
window.setInterval(function () {
var position = parseInt($banner.css('background-position'));
// minus is left, plus is right
if (position >= 0 ) delta = -delta;//go left
if (position < (-1*endpos)) delta = (-1*delta);//go right
position += delta;//increment posn
$banner.css("background-position", position + 'px' + ' ' + imgY + 'px');
$("#indicator").text('Posn:' + position + ' | direction: ' + delta);
}, 20);
});
CSS
div#canvas {
background-color: #999;
width: 100%;
height: 400px;
margin:0;padding:10px;
}
div#banner {
width: 460px;
height: 300px;
margin: 10px;
background: url(https://digido.net/eg/newcastle-beach-3000x300.jpg) no-repeat 0 0;
}
div#banner p {
font: 13px Arial, Helvetica, sans-serif;
color: white;
position: relative;
left: 0;
top: 310px;
width: 99%;
padding: 10px;
background: black;
text-align: center;
text-transform: uppercase;
letter-spacing: 8px;
zoom: 1;
filter: alpha(opacity=50);
opacity: 0.5;
}
HTML
<div id="canvas">
<div id="banner">
<p id="indicator">Hit run</p>
</div>
</div>

Just put the if condition inside the setInterval. And check the syntax error. The if doesn't have a closing }:
// scroll up background position every 90 milliseconds
window.setInterval(function() {
banner.css("backgroundPosition", x + 'px' + ' ' + y + 'px');
x++;
//x--;
if (banner.offset().left > 40) {
banner.css("backgroundPosition", "0px 0px ");
}
}, 90);

Your "if" should be like this:
if ($(banner).offset().left > 40) {
banner.css("backgroundPosition", "0px 0px ");
}
https://jsfiddle.net/wc4b2g97/

your if should be inserted inside your setInterval handler, so it would get evaluated every 90 milliseconds (thank you for correcting me).
Actually, your if is evaluted only the first time, when your javascript file is parse.
Add it into your setInterval and it should work as expected

Overlapping elements - HTML, CSS, and jQuery

I have elements which are overlapping and I would like to prevent this. Here is a picture: http://grab.by/cB7t
Also, here is the CSS for those elements:
.navigationItem {
background: #808080;
-webkit-border-radius: 360px;
padding: 1.0em;
text-decoration: none;
color: #fff;
position: absolute;
-webkit-box-shadow: 0px 2px 5px #909090;
font-weight: bold;
text-shadow: 1px 1px 2px #707070;
font-size: 1.0em;
}
And here they are in the HTML:
play
register
our blog
contact us
about us
our rules`
As you can see, I am using them as simple styled links using the HTML a tag. The reason that their positions are absolute is because I am moving them using jQuery:
function moveAll() {
for(var i = 0; i < AMOUNT; i++) {
var random = Math.random() * 500;
$("#nav" + i).animate({"left": random + i + "px"}, "slow");
$("#nav" + i).animate({"top": random + i + "px"}, "slow");
}
}
When they move, though, they sometimes overlap which is annoying. How can I prevent them from overlapping? Thank you for your efforts.

Removing position:absolute would render them side by side.
JSFiddle
But if the whole point is to scatter them around randomly, then you will have to keep track of positioned elements and take that into account when calculating their position. You should save each link's position and calculate every next link's position according to previous already positioned links. There's simply no other way when you want random positions and non overlapping.
Final non-overlapping solution
This is a working example of non-overlapping functionality. If you'd want your links to not even touch, you should change < to <= and > to >= in the if statement condition.
Relevant code
var positions = [];
$(".navigationItem").each(function(){
var ctx = $(this);
var dim = {
width: ctx.outerWidth(),
height: ctx.outerHeight()
};
var success = false;
// repeat positioning until free space is found
while (!success)
{
dim.left = parseInt(Math.random() * 300);
dim.top = parseInt(Math.random() * 300);
var success = true;
// check overlapping with all previously positioned links
$.each(positions, function(){
if (dim.left < this.left + this.width &&
dim.left + dim.width > this.left &&
dim.top < this.top + this.height &&
dim.top + dim.height > this.top)
{
success = false;
}
});
}
positions.push(dim);
ctx.animate({
left: dim.left,
top: dim.top
}, "slow");
});

You can change the position value to relative.
See my example : http://jsfiddle.net/NmmX6/2/
I changed your loop so that it isn't id dependent :
function moveAll() {
$('.navigationItem').each(function(i,e){
var rdm = Math.random() * 500;
$(e).animate({"left":rdm + "px"}, "slow");
$(e).animate({"top": rdm + "px"}, "slow");
});
}
I tested it and did not find one case where it actually overlaps, but check it out.