Get Current CSS Property Value During a Transition in JavaScript

Get current CSS property value during a transition in JavaScript

Is it possible to get the current css property during a transition in JavaScript?

Yes

var timer;
function test(e) {    var $this;    $this = $(this);    timer = setInterval(function () {        console.log($this.height());    }, 500);}function untest(e) {    clearInterval(timer);}
$('div').mouseenter(test).mouseleave(untest);

div{    transition: height 10s;    -moz-transition: height 10s;    -webkit-transition: height 10s;    width: 100px;    height: 100px;    background-color: #00F;}
div:hover{    height: 300px;}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script><div></div>

Is it possible to get the target css property value during a css3 transition in Javascript?

That's because .css('width') is calling getComputedStyle on the element, which does return the transitioning value. If you did directly access the style, you would get what you just had set:

document.getElementById('transition_div').style.width
$('#transition_div').prop('style').width
$('#transition_div')[0].style.width

(updated fiddle)

Get CSS value mid-transition with native JavaScript

It is very easy to port the jQuery script from the linked thread into its vanilla JavaScript equivalent and below is a sample. The output is printed on the right side (output#op element) once timer expires.

All that we are doing is the following:

• Attach two event handlers to the element which triggers the transition (sometimes the triggering element can be different from the one that has animation). In the other thread, the element that is triggering the transition and the one that is being transitioned is the same. Here, I have put it on two different elements just for a different demo.
• One event handler is for mouseover event and this creates a timer (using setTimeout) which gets the opacity and top value of the element that is being transitioned upon expiry of timer.
• The other event handler is for mouseleave event to clear the timer when the user has hovered out before the specific point at which we need the opacity and top value to be obtained.
• Getting the opacity and top value of the element that is being transitioned can be obtained by using the window.getComputedStyle method.
• Unlike the demo in the other thread (which uses setInterval), here I have used setTimeout. The difference is that setInterval adds an interval and so the function is executed every x seconds whereas the function passed to setTimeout is executed only once after x seconds. You can use whichever fits your needs.

var wrap = document.querySelector('.wrapper'),  el = document.querySelector('.with-transition'),  op = document.querySelector('#op');var tmr;
wrap.addEventListener('mouseenter', function() {  tmr = setTimeout(function() {    op.innerHTML = 'Opacity: ' + window.getComputedStyle(el).opacity +      ', Top: ' + window.getComputedStyle(el).top;  }, 2500);});wrap.addEventListener('mouseleave', function() {  clearTimeout(tmr);});

.wrapper {  position: relative;  height: 400px;  width: 400px;  background: yellowgreen;}.with-transition {  position: absolute;  top: 0px;  left: 100px;  width: 200px;  height: 100px;  background: yellow;  opacity: 0;  transition: all 5s linear;}.wrapper:hover .with-transition {  top: 300px;  opacity: 1;}output {  position: absolute;  top: 50px;  right: 50px;}

<div class='wrapper'>  <div class='with-transition'></div></div><output id='op'></output>

How to change CSS property by JS and use transition?

Firstly you are setting the transition of the --webkit-filter property, but you set the filter property.
Secondly as jneander mentioned the change is happening too quickly you should wrap it in a requestAnimationFrame or a 1ms timeout

Here is a working demo with the fixes:

let value = "15px";
let loadImg = document.getElementById("block");

let transitionDuration = "1s";
let timing = "ease-in-out";
let delay = "1s";

loadImg.style.filter = `blur(${value})`;
requestAnimationFrame(()=>{
  loadImg.style.transition = `filter ${transitionDuration} ${timing} ${delay}`;
  
  loadImg.style.filter = 'none';
});

#block {
  width: 150px;
  height: 150px;
  background: red;
}

<div id="block"></div>

Javascript Get Element CSS Transition Stage

You can assign a property in the animation and retrieve this property value to know the animation stage. For instance, asign z-index a value between 100 and 200:

click the element to show the percentage of the animation

function showStep () {    var ele = document.getElementById("test");    var step = getComputedStyle(ele).getPropertyValue("z-index") - 100;    ele.innerText = step;}

#test {  position: absolute;  width: 400px;  height: 200px;   border: solid red 1px;   -webkit-animation: colors 4s infinite;   animation: colors 6s infinite;  font-size:  80px;  color:  white;}

@-webkit-keyframes colors {  0% {background: red; z-index: 100;}  50% {background: blue;  z-index: 150;}  100% {background: yellow; z-index: 200;}}
@keyframes colors {  0% {background: red; z-index: 100;}  50% {background: blue;  z-index: 150;}  100% {background: yellow; z-index: 200;}}  

<div id="test" onclick="showStep();"></div>

Cannot get CSS transition property with jquery in Firefox

Actually this is weird that transition property is empty, but other properties that transition consists of are accessible, so you can concatenate whole transition value. You can get CSS properties values by using getComputedStyle method, as well. Your console should print out every property except the first one and delay value (if you don't provide it), which is empty string:

var element = document.getElementById('transitionElement'),
    style = window.getComputedStyle(element);
    console.log(style.getPropertyValue('transition'));
    console.log(style.getPropertyValue('transition-delay'));
    console.log(style.getPropertyValue('transition-duration'));
    console.log(style.getPropertyValue('transition-property'));
    console.log(style.getPropertyValue('transition-timing-function'));

Always remember also to provide vendor prefixes for older versions:

#transitionElement {
    -webkit-transition: all 0.5s ease-in-out;
    -moz-transition: all 0.5s ease-in-out;
    -ms-transition: all 0.5s ease-in-out;
    -o-transition: all 0.5s ease-in-out;
    transition: all 0.5s ease-in-out;
}

How to use CSS transition during accumulation on JS? (Code suddenly doesn't work)

It is probably due to internal optimisations. What is happening is that the browser is batching changes to the styles and adding them all together, even if you add them separately. This means that the left is not being transitioned. The same happens if you try to transition any property together with display: none to something else.

If the browser was not doing this optimisation before, they are now doing it, that's why your code is broken.

There is a simple solution to this, which is to run stock in a callback to setTimeout, like this: setTimeout(() => this.stock(S2N), 0);. This opts you out of the optimisation by scheduling the change at a later time (even if it's 0ms, it's still added to the queue and not executed immediately, thus the opt out). You can see this working in the snippet below. This is the easiest fix.

Another possible solution is to calculate the percentage yourself, instead of setting the display: none to get the percentage value. As far as I understand, this behaviour is not well defined and it might change in the future. You could instead calculate the percentage of your left value like this:

Math.floor(window.innerWidth / parseInt(currentProp, 10))

You could do it during the instantiation of the Assemble object or create some kind of logic inside the class that detects if the unit is a percentage.

A final word of warning: transitioning left is rather inefficient. Try transitioning the transform: translateX(value) property. It's much better for rendering performance.

'use strict';class Assemble {    constructor(elem, acc, name, unit) {        this.elem = document.querySelector(elem);        this.acc = acc;        this.name= name;        this.unit = unit;    }    calc() {        let displayOn = this.elem.style.display;        this.elem.style.display = 'none';        let currentProp = window.getComputedStyle(this.elem, null).getPropertyValue(this.name),            S2N = parseInt(currentProp, 10);        this.elem.style.display = displayOn;        if (S2N < 100) {            setTimeout(() => this.stock(S2N), 0);        }    }    stock(value) {        let digit = (value * 1) + this.acc;        this.elem.style.left = digit + this.unit;        this.elem.addEventListener('transitionend', this.calc.bind(this), {once: true})        console.log(this.elem.style.left);    }}let proAssemble = new Assemble('.button', 10, 'left', '%');proAssemble.calc();

* {    margin: 0;    padding: 0;}.button {    position: absolute;    width: 200px;    left: 0;    background-color: purple;    transition: left 1000ms;}

<div class="button">    test</div>

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