We Keep Coding

How to increase speed of mousemove/clientX/Y and applying a transform?

I have built a WordPress theme. I came across a website that created a div to follow the user's cursor. The div was enlarged smoothly when the user hovers over a button or a link.
I want to add this nice functionality as an optional feature.
I added a div to the web page, #ambition_cursor and added some basic styling. The div now shows like a blue circle. The circle has position fixed to the top left corner of the site. The position can be changed by adding a CSS translate property.
I managed to make it work with the following code:
var ambition_cursor = document.getElementById("ambition_cursor");
function ambition_mouse(e) {
var ambition_cursor_x = e.clientX; // Get the horizontal coordinate
var ambition_cursor_y = e.clientY; // Get the vertical coordinate
var ambition_cursor_pos = `translate(${ambition_cursor_x}px, ${ambition_cursor_y}px)`;
ambition_cursor.style.transform = ambition_cursor_pos;
}
window.addEventListener('mousemove', ambition_mouse);
The big downside here is the lag (?). There's quite a big delay, especially when moving the mouse around very fast. You can try it out on this site. I also put the situation in a JSFiddle; although the delay doesn't really happen there.
I didn't apply yet much styling (the default cursor is visible, so you can get a better idea of the real position). I first want this to work better, before I spent much time on that.
How can I increase the speed of this, so that the div position follows the mouse more accurately? I'm a beginner, so I don't really know which JavaScript optimisations I should make.
Current code is JavaScript, but jQuery is also an option.
Many thanks in advance!
Update: example how it looks on my computer.

All elements on the page have a transition applied. Remove/override this style and the delay goes away (tested).

As an alternative to the great answer of Joseph Atkinson:
var ambition_cursor = document.getElementById("ambition_cursor");
function ambition_mouse(e) {
ambition_cursor.style.left = e.clientX + 'px'; // Get the horizontal coordinate
ambition_cursor.style.top = e.clientY + 'px' ; // Get the vertical coordinate
}
window.addEventListener('mousemove', ambition_mouse);
See: https://levelup.gitconnected.com/use-javascript-to-make-an-element-follow-the-cursor-3872307778b4

I visited the site example, cracked open the dev console, and found throttled(20, ambition_mouse) It is not a performance issue, and the solution is to not throttle the events. It was too smooth to be a performance issue, which gave me the first clue it had to be an accidental/deliberate effect.

Flexslider breaks jQuery accordion [duplicate]

I have a test page to better explain my problem. I have several items on a list (they're images on the test page); when I click on one of them, a corresponding slideshow, using flexslider, sldes down.
The problem is that, on page load, the slideshow shows all slides at once, at a much smaller size than intended. But then, if I switch the focus from the window (i.e. switch between browser tabs or move to another program and come back), the slideshow is now working and the slides are the proper size. This happens in mobile devices too.
When I check with firebug, there's an element.style rule applying to ul.slides:
transform: translate3d(-89px, 0px, 0px);
Which hides one of the slides. Additionally, there's another rule for the list items inside ul.slides that gives them their initial width, which is not even the same for all sliders so I don't understand where it is coming from.
Can someone take a look and suggest a fix? I've tried overriding the element.style rule but so far unsuccessfully.

I think I've figured it out, in principal at least...
.flexslider{display:none;} seems throw off the re-size function of Flexslider.
You could just remove it, but that makes for some ugly loading.
To avoid said ugly loading I put together a quick, work-around- jsFiddle
$(document).ready(function(){
$(".flexslider").css('display','block').slideUp();
});
There's a still a quick glitch while loading, but hopefully it will at least steer you in the right direction.
Another method I played with a bit was to try and force the re-size function like so-
$(".client").click(function () {
$('.flexslider').resize(); // Problematic but promising
var project = this.id;
var project_id = '#' + project + '-project';
var elem = $(".flexslider:visible").length ? $(".flexslider:visible"): $(".flexslider:first");
elem.slideUp('slow', function () {
$(project_id).slideDown('slow');
});
});
This sort of solved the mini-picture issue, but was spotty at best.

Why is my javascript only working when the part of the page it acts on is visible in the browser?

So I am using the slick image slider and everything was working great until I considered what would happen if images of different heights were put in. I then wrote a short piece of js to check which image is the tallest and set the heights of all of them to that height.
window.onload = imageSlideChange;
$(window).resize(imageSlideChange);
function imageSlideChange(){
var tallestImage = $('.slick-slide').first().height();
$('.slick-slide').each(function(){ //.slick-slide is the class of each image
if($(this).height() > tallestImage){
tallestImage = $(this).height();
}
});
$('.slick-slide').each(function(){
$(this).height(tallestImage);
});
}
The weird thing though is the code only runs correctly when the slider is in the browser window. If I scroll to the bottom or top of the page and reload it will only load the images as 1px height. I thought maybe it was the images not being loaded and set the function to only run on window.loadbut beyond that I don't know what could cause this kind of behavior.
When you go to inspect the images they are the correct height. The 1px must be coming from their default height, which means that when the code runs it must be reading their heights as 0. Why???
If it helps this is all happening as drupal serves up the images, so could that be the problem?

A white bar appears at the bottom of my website sometimes, how to get rid of it?

I have a personal website I'm working on where the background image moves with the time of day.
At the bottom of the page, I have jQuery UI tabs going for my menu.
The background image moves up and down, this is my function I wrote:
// Move background based on current time
function backgroundMove() {
var windowHeight = $(window).height();
var imageHeight = 1200; // Background image height
//CODE
$('body').attr("style", "background-position: 0px " + movement + 'px');
}
Now on my local machine, this method works flawlessly, the background moves as it should. But when I put it online, sometimes a solid white bar shows up at the bottom. The background image is where it should be, position-wise, but it gets cut off with this bar and thus you can't see my menu anymore (it is all-white tabs).
Since it doesn't happen consistently I've had trouble identifying the problem. Does anyone have any ideas as to what it might be, how I might fix it so it doesn't happen again?

Try adding this:
height:100%; overflow:hidden;

jQueryui animation with inital undefined height

See the following fiddle:
[edit: updated fiddle => http://jsfiddle.net/NYZf8/5/ ]
http://jsfiddle.net/NYZf8/1/ (view in different screen sizes, so that ideally the image fits inside the %-width layouted div)
The image should start the animation from the position where it correctly appears after the animation is done.
I don't understand why the first call to setMargin() sets a negative margin even though the logged height for container div and img are the very same ones, that after the jqueryui show() call set the image where I would want it (from the start on). My guess is that somehow the image height is 0/undefined after all, even though it logs fine :?
js:
console.log('img: ' + $('img').height());
console.log('div: ' + $('div').height());
$('img').show('blind', 1500, setMargin);
function setMargin() {
var marginTop =
( $('img').closest('div').height() - $('img').height() ) / 2;
console.log('marginTop: ' + marginTop);
$('img').css('marginTop', marginTop + 'px');
}
setMargin();

Interesting problem...after playing around with your code for a while (latest update), I saw that the blind animation was not actually firing in my browser (I'm testing on Chrome, and maybe it was firing but I wasn't seeing it as the image was never hidden in the first place), so I tried moving it inside the binded load function:
$('img').bind('load', function() {
...
$(this).show('blind', 500);
});
Now that it was animating, it seemed to 'snap' or 'jump' after the animation was complete, and also seemed to appear with an incorrect margin. This smacks of jQuery not being able to correctly calculate the dimensions of something that hadn't been displayed on the screen yet. On top of that, blind seems to need more explicit dimensions to operate correctly. So therein lies the problem: how to calculate elements' rendered dimensions before they've actually appeared on the screen?
One way to do this is to fade in the element whose dimensions you're trying to calculate very slightly - not enough to see yet - do some calculations, then hide it again and prep it for the appearance animation. You can achieve this with jQuery using the fadeTo function:
$('img').bind('load', function() {
$(this).fadeTo(0, 0.01, function() {
// do calculations...
}
}
You would need to work out dimensions, apply them with the css() function, blind the image in and then reset the image styles back to their original states, all thanks to a blind animation that needs these dimensions explicitly. I would also recommend using classes in the css to help you manage things a little better. Here's a detailed working example: jsfiddle working example
Not the most elegant way of doing things, but it's a start. There are a lot more easier ways to achieve seemingly better results, and I guess I just want to know why you're looking to do image blinds and explicit alignment this way? It's just a lot more challenging achieving it with the code you used...anyways, hope this helps! :)